Windows Vista was a hog, but Windows 7 will run on any system that Ubuntu does, and runs well on the same systems, although you may have to disable Aero. The Windows 8 developer preview is actually faster and uses less memory that Windows 7, but it does require a "DirectX 9" graphics card (most anything 2002+), as the graphics are 100% 3D-accelerated.
Win7 also remarkably stable from what I've seen for the past 2 years or so. It's not subject to the junk XP was, like having to run ipconfig /flushdns (or rebooting) to fix network issues. It also uses ASLR and DEP by default for base security purposes.
Because of that, there's no reason to use XP in the Windows world ofr anything except for 1990s-era software that requires IE6 or does things like write to its own C:\Progra~1\ directory. Not to mention XP considers SATA to be exotic hardware, drivers haven't been written for it for years, its PnP driver capabilities are way outdated, etc.
But whatever you're using, it's your choice, and do enjoy. Just thought I'd inform you on this from the other side of things. :)