Mac OS X doesn't have that feature anymore, although one can use Terminal for that.
You are absolutely right! According to your first link, it will "Archive and Install" automatically over a newer version (and it doesn't leave a "Previous Systems" folder behind anymore).
So, to Hexero — You have 3 options:
- Stay at 10.6.4 and try and make it better — Do some maintenance steps and see if that helps.
- Archive and Install — Keeps your Applications, Users, Documents, and Preferences, but you get a fresh OS install.
- Format and Install — Wipe your Mac's Hard Disk (you can keep Bootcamp) and reinstall a fresh OS X with no Applications, Users, Documents or Preferences saved.
Option 1 involves checking your hard disk for errors and for permissions problems (these have gotten more rare over the years but can still cause strange problems with OS upgrades.) Preferences file problems can cause system and application problems, so moving your preferences out of the preferences folder and to a folder on your desktop and rebooting can often cure strange problems (the preferences will be rebuilt). There are other things you can do as well.
Option 2 is probably the easiest if you just want to downgrade to 10.6.3. Just reboot with the Snow Leopard DVD (Insert the DVD, reboot the mac, then hold the C key until the Apple appears.) Follow the instructions to install the OS and when its done you will be at whatever version came on the CD. Then you can download the 10.6.3 updater from Apple if needed.
Option 3 only differs from option 2 in that once the installer has loaded and you get to the screen where you choose the disk to install on, choose "Disk Utility" from the "Utilities" menu. Once that loads, click your Mac HD on the left (not the icon that says XXX GB or TB, and not the Windows partition. If in doubt, when you have the correct one selected, it will say "Format: Mac OS Extended (Journaled)" in the bottom of the window. If it doesn't have a line that says that then you have the wrong one selected.) Click Erase on the right, then Erase again. This
will erase your files, apps, iTunes purchases, etc., so
be sure! When it's done erasing, quit Disk Utility and proceed with the install. Download the 10.6.3 updater from Apple if needed.
Hope this helps! If you need any more explanation of the preceding, just post and I'll try and answer. If not, somone else surely will! (Hooray MacRumors!)