It's an old Radeon 7500 which on XP supports the 100Hz refresh rate so the monitor won't flick at 1152x864. On W7 it just installs generic VGA drivers which won't allow highish refreshing rates, nor my preferred resolution.
I've tried to install several different drivers for Ati cards, almost everything I've been able to find, but most of them simply won't get installed. Some seem to go through, but in the last step, they don't install, so W7 keeps the generic VGA. I keep checking Ati site, but they don't seem to be interested in releasing W7 drivers for such an old GPU.
I'd rather keep using XP than getting a new GPU for this computer