Vista works O.K. now that the 3rd party programs have caught up on their drivers. Vista is a flat out memory hog and uses about 2 gigs of memory just to run the operating system. You can speed it up some , by disabling the widgets.
I build gaming computers as a hobby .and have installed window 32 bit Media, XP Pro 32 and 64 bit ,Vista 64 and Windows 7 Pro 64 bit on my personal computer. AMD 4 core, 2 500 gig hard drives Raid 1 , 8 gigs DDR3 and 2 Nvidia GTX 9800 + 500 mb graphics cards in SLI. The jump between Vista and Widows 7 was huge. The speed went from fast , to super fast . I haven't timed it , but cold boot isaboutunder 45 seconds . The graphics are much much better
Window 7 runs G4.5 and G5.0 without any issues. Some of my older software ,I had to run in compatibility mode ,but it well run them.