It seems that the 2.6.17 base doesn't detect videochips correctly:
SiS chipsets get their resolution set to really low
Ati chip doesn't get recognised [neither do the SiS ones], but gets it normal resolution at my laptop. Both get set to use vesa.
.xsession-errors does say:
Xsession: X session started for morph at Sat Nov 18 09:28:31 EST 2006
** Message: This build doesn't include support for XF86Misc extension
** Message: Querying Xkb extension
** Message: Xkb extension found
** Message: Querying Xkb extension
** Message: Xkb extension found
[I guess the latter four lines are superfluous, but there for completion anyway].
Logged In: YES
user_id=784103
Originator: YES
The ATI card is a Mobility Radeon 9700 [RV350], I don't know about the SiS ones. It seems the 0.5-pre6 official base didn't recognise this ATI too, but it seems to work better at least.