This entire thread is pathetic.
If you're looking for help with a problem, don't post here thinking people will treat you nicely after you bash the **** out of Apple's new OS. If you stopped by the Genius Bar, would you explain your problem as "screw apple, this operating system must be a piece of crap because it's running as slow as my old windows machine"?
Next time you post, why don't you clearly state the problem you're having as well as any variables that may have caused a problem. Whether your system is two days, two weeks, or two months old - that does not mean that it's exactly the same as out of the box. I'm sure there is software installed that may be incompatible, hardware you have hooked up, or old PrefPane installs that are driving the OS crazy. Did you update your firmware to the latest release? Was your drive corrupt?
Granted the install disc should "just work," there's a lot of user error that can still cause problems.
Many people are having a great experience in 10.6, yet you don't want to hear how they managed to get everything working properly.
I'm sure with the amount of developers testing SL, and the small number of Intel-based machines (really, it's not that big of a number), almost every system setup has probably gone through with this install. I'm also sure that Apple knows what it's doing. Snow Leopard isn't that big of a change (other than a few rewrites / optimizations) from the original Leopard code, so there shouldn't be many problems.
But for you, here is my detailed suggestion:
1. Check your updates / Utilites folder for a firmware upgrade. Read the instructions if you have one. If you do it right, there will be a box explaining so on your restart.
2. Download iBackup for free at MacUpdate.com and use an external to back up the settings and folders you'd like. Make sure you set where it's going at the top. I would not recommend copying Keychains or Applications. Stick to general settings (Mail, iTunes, Safari, etc.) and don't backup anything you can configure on your own. Make sure to backup the folders you are sure you'd want, like your Desktop, Music, Photos, Downloads, Documents, etc.
3. Write down the exact name of your home folder.
4. Put in the Snow Leopard disc, and shut down your computer.
5. Start up holding the C key until you see the spinning gear under the Apple logo. You will hear the DVD spinning and reading, but it might take a minute.
6. Choose Utilities from the top menu of the SL disc, and select Disc Utility. Chose your drive on the side, click the Erase tab, Security Options, and erase using a single pass of Zeros. This will take about 30m, but will insure a clean install.
7. Close the Disc Utility and install Snow Leopard.
8. After the install, Spotlight might slow down your computer because it's looking at your drive. Let it sit if this is the case.
9. Open nothing but Safari, and download iBackup again. Close Safari, install, and open your backup. Start the migration. Be aware that Spotlight will go insane afterwards with indexing, and be prepared to let it sit again.
10. On completion, open the programs that used your old settings - Mail, Safari, iTunes - and let them upgrade your settings.
11. Restart
12. Go to Disc Utility, in the Utilities folder, and Repair your disk permissions.
13. Check for updates, and install 10.6.1
14. Restart after it restarts
15. Repair disk permissions again
16. Check for software incompatibility / updates before you install the software you need. Install everything you'd like, and open the programs one by one. If you installed Apple software, update via Software Update after installtion - and before you open the app.
17. Restart
18. Repair Disk Permissions
19. Shut Down, and unplug everything from your computer for 1 minute.
20. Plug back in. Start up holding down Cmd+Option+P+R until the second chime.
21. Go to System Preferences and re-select 10.6.1 as your startup disc.
22. Restart and enjoy error free computing.