I use CS. Its the same thing as 7 but with a filter gallery, which can help. But it can be a nuisance.
I think CS is better, but then, that's my opinion, and what I use. And you don't need winxp to run CS.
I have 7 which is paid for legally. I was a beta tester for CS. But it didn't have keyboard short cuts which was alright, and i got CS which i didn't like at all. It took about 2 minutes to load, and that's with no brushes installed. Now with 7 it takes 15 seconds maybe.