update: ok, so when i tried the agpmode option, it worked with agpmode 1, but not with agpmode 2 or 4.
for the record, lspci shows the following on the video card:
01:00.0 VGA compatible controller [0300]: ATI Technologies Inc Radeon R250 [Mobility FireGL 9000] [1002:4c66] (rev 02) (prog-if 00 [VGA])
update: ok, so when i tried the agpmode option, it worked with agpmode 1, but not with agpmode 2 or 4.
for the record, lspci shows the following on the video card:
01:00.0 VGA compatible controller [0300]: ATI Technologies Inc Radeon R250 [Mobility FireGL 9000] [1002:4c66] (rev 02) (prog-if 00 [VGA])