You should try some of the Linux-based operating systems. Yesterday I installed new Ubuntu. Prior doing that I backed up my root partition (I have /home - something like Documents and Settings - on different partition). I merely copied files to my USB disk. Took like 10 minutes for 8 gigs of data. Then I installed Ubuntu 7.04, hated the fonts, convinced that they're different than in 6.06 (or the rendering is different), I restored my backup back to 6.06. Just copied the files. 10 minutes.
In unix world, you usualy just copy the files!
No stupid registry things. (Ok, let's forget for a second that there is gconf :( )
Using Debian then and now Ubuntu I have much less fuss than I it with Windows. Ok, I am quite familiar with Debian, so Ubuntu is a breeze, but 7.04 is realy realy realy user friendly! It downloads the codeces and stuff automaticaly, all you have to do is say 'yes, buntu, do it for me!'. Neat! :)
The only thing I'm missing from Windows world are games. Yes, there is Quake and UT and likes, but I miss Need for Speed and Age of Empires.... They run under Cedega, but they're unplayable (P4@1.7+768MB+Radeon9600 - those work under WindowsXP quite well).
Seriousley, try Ubuntu (or any other distro, but I feel that you'll have least fuss with Ubuntu), and see how thigns are done there. Then, maybe, you'll see why UAC concept is not that good, esp. the way Microsoft implemented it.