I can Echo what GunHo said, Easiest OS install for me to date, and much quicker than Vista install, espically without determining your performance index. I was surprised to see that setup even automatically installed my networked HP printer. UAC is so much less bothersome, I haven't even disabled it. I wasn't sure I would like the taskbar when others were talking about it, but I think it's great and it actually gives the useful information I want, instead of the little picture that Vista gives which looks nice but is not clear enough to be useful. I threw in 2 extra gigs of RAM so I could try out 64-bit, so I can't comment on how the great performance I am seeing would translate into 32-bit. The nVidia drivers are very good, (glad they learned their lesson from Vista) and everything on the desktop is exceptionally clear when compared to XP. I put an extra drive in my system for Windows 7 and the bootloader makes it easy to switch between XP and 7. So far the only thing I have installed is AVG 8, which works fine. I tried Avast, and it installed correctly, but when I rebooted the AV engine cound not be started.
I have Vista on my laptop (came with it) but did not upgrade my desktop from XP. Because 7 runs so well, looks great, and has a nice feature upgrade from XP, I plan on buying it when the full version is released. It would be a great upgrade from XP, but I will leave Vista on the laptop. I may be in the minority, but I have had very few and minor quibbles with Vista. I just don't see any reason to buy Vista for the desktop when 7 is right around the corner and seems to be a better OS.