NOTE: The most up-to-date steps are available in the following Guide entry: http://guides.macrumors.com/Complete_Steps_to_Perform_a_Clean_OS_X_Reinstall_on_Your_MacBook_Air. Please feel free to post your questions and comments in this thread. This guide is provided in order to make it easier for you to free up valuable hard drive/SSD space on your MacBook Air by reinstalling OS X with only the components that you really need. It is recommended that you perform these steps before you install a bunch of applications and data files, because these steps will reset your MBA's hard drive/SSD completely. STEPS TO PERFORM A CLEAN INSTALL: Insert your OS X DVD #1 into your SuperDrive (if you have one) or external, shared DVD drive (you must have set this up previously, following Apple's instructions and using the OS X DVD #1 in your remote machine to install Remote Disc). Shut down your MacBook Air. Then, turn it back on and hold down either the C key (SuperDrive) or the Option key (Remote Disc) to boot from the OS X DVD. The Apple logo will come up and the "processing" whirly thing will go for a while (a few minutes, in my case). The screen will eventually turn blue, and then you will see the nebula wallpaper and be prompted to select a language. Click "Use English for the main language", or select your appropriate language. Then, click the "-->" button. The Mac OS X Leopard Installer window will appear. On the Utilities menu, click Disk Utility. The Installer window will disappear and the Disk Utility window will appear. Once disk information has been gathered, select your hard drive. This will be the item ABOVE "Macintosh HD". In the case of a 64 GB SSD, the item should be called "55.9 GB MCCOE64GEMPP" or something similar. Click Partition. Under Volume Scheme, select "1 Partition". In the Name box, type "Macintosh HD" or whatever you want your hard drive to be named. Then, click Apply. Click Partition to confirm repartitioning of the hard drive/SSD. It will take a few seconds for the drive to be partitioned. Once it's done, click Quit Disk Utility on the Disk Utility menu. The Disk Utility window will disappear and the Installer window will reappear. NOTE: If you fail to perform steps 4-6, you will not have a clean install, and it is possible that you will not be able to prevent applications from being installed. In the Installer window, click Continue. Click Agree to agree to the software license agreement (you can read it first if you really, really want to). In the "Select a Destination" window, select your hard drive ("Macintosh HD" or whatever you called it). Click Continue. In the Install Summary window, click Customize (lower-left corner of the dialog box). In the list of Package Names, you can turn OFF (uncheck) any or all of the following items, depending on whether you think you will ever need them: PRINTER DRIVERS (3.4 GB): You can opt to not install ANY printer drivers by clearing the Printer Drivers checkbox. You can also install just specific printer drivers by turning ON only the checkboxes for those printer drivers you think you might need (Hewlett-Packard, for example). In my test, I turned the Printer Drivers checkbox OFF and chose not to install ANY printer drivers; later on, I plan to manually install the printer drivers for my specific HP printer using the CD that came with the printer, and I don't need any other drivers. ADDITIONAL FONTS (141 MB): I don't ever need Chinese, Korean, Arabic, Hebrew, Thai, Cyrillic (Russian), Devanagari, Gujarati, Punjabi, Tibetan, Armenian, Cherokee, or Inuktitut font support for my own use, but I occasionally do hit web sites that use one or more of these languages, and it's only 141 MB... so I left this checkbox turned ON. If you want to save 141 MB because you're sure you won't need this, you can turn the Additional Fonts checkbox OFF. LANGUAGE TRANSLATIONS (1.8 GB): I definitely don't need any of these, so I turned OFF the Language Translations checkbox and chose not to install any of them. Individual languages may be installed by turning ON their checkboxes... each language is roughly 100 MB in size. X11 (117 MB): This option allows you to run Linux and UNIX apps in OS X. I don't think I'll ever do this, but I left the option checked since it's only 117 MB. (EDIT: Thanks to mzd for explaining what this option does.) BUNDLED APPLICATIONS (3 GB): This contains many separate items which you may or may not want to install: CPU HELP FILES (262 MB): This is the user's manual for the MBA and for Leopard, so this is probably a good thing to install. IWEB (290 MB): I don't use iWeb for web design. Ergo, I cleared the checkbox for iWeb and chose not to install it. GARAGEBAND (1 GB): I don't really use GarageBand except to make ringtones for my iPhone... and I'll be doing that on my mac pro. So, I cleared the checkbox for GarageBand. Note that the "GarageBand Additional Instruments and Loops" option (1.3 GB) is turned OFF by default. IDVD (559 MB): No built-in optical drive = no making DVDs on my MacBook Air, so I cleared the checkbox for iDVD. As with GarageBand, the "iDVD Extra Content" option (342 MB) is turned OFF by default. IPHOTO (553 MB): This was a tough one for me. I don't plan on managing my photos on my MacBook Air, but I can see where I might want to at some point. So I left this checkbox turned ON. IMOVIE (136 MB): As with iDVD, I can't see using iMovie on a machine with no optical drive built-in (although I suppose you could just author movies and then burn them when you get home). At any rate, I don't ever use iMovie, so I cleared its checkbox. By my reckoning, turning OFF the items listed in blue above should have saved me 7200 MB or so (7 GB?) in disk space (actual numbers below). Once you've made the changes you want, click Done. Then, click Install. Click Continue Installation once you verify you have both OS X DVDs. You can click Skip if you want to skip the DVD consistency check. This will save you a lot of time in the installation process. I clicked Skip and was told that installation would take roughly 40 minutes to 1 hour. When the Installer is done with OS X DVD #1, the MacBook Air will automatically restart and eject OS X DVD #1. When this occurs, go ahead and insert OS X DVD #2; YOU MAY NOT BE EXPLICITLY TOLD TO INSERT THE DVD. Insert the DVD and installation will continue automatically for about 10 to 20 more minutes. When installation is complete, you will be prompted to click Continue. OS X DVD #2 will be ejected and your MacBook Air will automatically reboot and you will go through the normal first-time experience (selecting language, entering Apple ID, creating user account, etc.). Following these steps, I went from: FACTORY CONFIG Used = 18,563,555,328 bytes Free = 38.29 GB to CLEAN INSTALL Used = 10,813,370,368 bytes Free = 45.51 GB for a total savings of 7.22 GB! That's almost a 19% increase in free disk space, and it only took about an hour and a half to do. Turning off other options which I chose to install might have saved me about 1 GB more. Note that once you have installed the above, you will still need to install OS updates (OS X 10.5.2, etc.) and application updates using Software Update. Hope these steps help... please post your comments here and I will update these steps as necessary. MORE THINGS YOU CAN REMOVE MANUALLY: Deleting the Alex voice (thanks to actuality for that tip) would free up almost another 700 MB, but this can be done at any later time. And using the steps that Salty Pirate documented below would free up another 2 GB, but I don't want my system crashing if I let the battery completely drain, so I am passing on that for now. ADDING COMPONENTS BACK IN LATER ON: If later on you want to install something you chose not to install using the above steps, you can insert the OS X DVD #1 into your DVD drive (SuperDrive or shared Remote Disc) and then double-click Optional Installs > Install Bundled Software Only > Continue > Continue > Customize. This will let you (re)install the CPU Help Files, iWeb, GarageBand, iDVD, iPhoto, and iMovie. MORE WAYS TO SAVE SPACE: Click here for some handy information about how to store your files on a different machine and still be able to access them from your MBA.