Definitely agreed.... I just updated my laptop with the latest Ubuntu 9.10 "Karmic Koala". It's fantastic... ridiculously fast bootup / shutdown... and if you're used to Windows.. Ubuntu will be a good Linux distro to ease into, especially for a tech-savvy guy like yourself
However Pete, have you tried installing a Windows 7 driver for the video card? I'm just guessing but it sounds like you might be running a driver that Windows 7 chose for you... which works, but given the situation, I would recommend to try and manually install a driver for it. (Possibly Windows 7 chose a Win Vista driver because ATI hasn't updated the driver yet?) I remember running the release candidate, I had to do that with my nVidia 9800GT video card. (Had black out issues).