just to let all Shuttle ST20G5 users out there that you can install Windows 7. It has taken me a few weeks to find a working driver. I even tried extracting one from Vista 64 which worked on one of my ST20G5s but not on the other!
As I haven't made a minimum 5 posts before I can insert a link in a thread then reconstruct this: paulmcgrath dot net
You'll find the driver in the downloads.
It contains a Vista 32 and 64 driver which I have working in Windows 7 64bit (I am online on it now).
With a X2 4200, 1.5GB ram and a NVidia Geforce 9400 GT my performance rating is a respectible 4.5 out of 7.9. My ram let me down! It is just DDR 333.