Yeah there really isn't much difference at all between 2000 and XP and 2007 and 2010. They all do the same sort of thing. Office 2010 is my favourite though, I just like the UI and the speed of it.
I still run XP Pro. because it is most stable and I know it the best. My computer is a Dell Inspiron 530 with a Intel Core 2 Duo @ 2.33Ghz and 3 GBs of RAM. A 320 Gig HDD and a external 1 TB my passport HDD. I had Windows 7 and Vista on it at one point.