OK, guys, here's the word!
I ran XP for a few days, and I had a few problems with it. First of all, I am used to (and I like) Vista, which means that going back to XP feels a bit bad. I especially like the way Vista handles network connections and some other stuff, and of course I really dont like the way XP looks - which is a minor thing, but still a bad thing. What really made triggered my anger was the fact that despite my XP setup is from the factory, I had two crashes already (!), both during shutdown procedure - and I haven barely installed any software.
I tried installing RC7 on another parition, and MAN - I turned off some of the more flashier things in Aero, but didn't disable Aero completely, and it flows much better than XP. And thus far safer and smoother. It looks better, it has some nifty features and it handles networks better (in my opinion). Not to mention it doesn't crash (yet).
Something that really bugs me is that I can't seem to run OpenOffice on RC7. It won't even launch installation - and somehow the installation file was just deleted when I tried to launch it, post error!? Since I love OpenSource and prefer not to use pirated copies, I really don't want to go with Microsoft Office. Anyone got any clues here?
Furthermore, I will save the XP partition as backup in case of RC7-failure, even though I have a hard time seeing how such a great system could fail me... ;-)