I don't understand why everyone seems to like Windows 7. I've tried XP and Windows 7 on the same machine (a new mid range system) and it runs much smoother on a tweaked XP than it does with Windows 7. Win7 has so many retarded and annoying features and I hate the start menu.. XP in proper classic mode is way better, I wouldn't even call Windows 7 a professional operating system.
Windows 7 is designed for more modern PC's. Sure it will run on older systems but to get the best benefits you need a half decent system that can support Aero, etc.
I am not a fan of the start menu. You can tweak it and get it looking 'classic like' which I have done but that's about it.
It's so much better than XP - XP you'd have to reinstall or mess around with to keep it running well where as with Windows 7 it just works. No blue screens, etc. and it gets everyone moving in the right direction towards 64 bit processing.
With regards to operating systems it's time to actually move with them - it was £50 on release which is an absolute bargain for what it offers. If you really can't see the difference between the two then you simply haven't really used it. You've probably installed it and gone 'don't like this - it's different' and then gone back to XP.
It's certainly a much more professional OS than XP - simply due to the lack of maintenance required from the end-user and also the reliability. It's also a lot more secure with UAC, etc.
M.