think of w7 though as a fixed up vista. it works pretty good and there are hardly any bugs.
as far as linux goes, you won't be able to use alot of the same apps...but there are other apps out there that do the exact same thing. There's always an alternative. If you google "linux replacement for [insert windows prog here]" you'll find something.
Only thing I'd need desperately is Photoshop (cause i still don't like GIMP) and a way to cycle through my wallpapers (haven't looked into that yet).
SimplyMEPIS failed to load a GUI for me. So the CD was tossed.
LinuxMint is fun. I see why my g/f likes it....instead of giving you an error, it explains everything to you, and what commands to go run in terminal to go fix it. Only problem is that getting my RT2870 wireless chipset working on it IS NO WALK IN THE PARK AHHHH so I may just pop in an old wireless g card i have laying around. But it has a few things that are pretty nice features I think. "Start Menu" is almost like the vista one, but it is already organized for you. Friendly reminders all around. They even have a fairly stable x64 branch too.
http://www.linuxmint.com/Haven't tried Wolvix or the 90mb XP iso yet.