if i have the a onboard what shall i select?

i'm using:
pentium 1 prolinea 575
linux: mandrake 9.2

Nvidia is good with Linux.

Ditto. In this system, look for a NVIDIA TNT2 card. Look for a card that is compatible with this older system, such as a 2x AGP if the system has an AGP slot.

If no AGP slot, a PCI can be used, but on some systems, you need to set the bios to use PCI over the onboard. Consult the manual on this issue.

As I mentioned in your other post thread, yea old Cirrus Logic (which is probably what you have onboard) is giving you the headache.

Correct me if I am wrong.

ok, now i founf\d somethin in my hardware.. cirrus logic GD5434 but still it's giving me error's

imn personally a nvidia person, plus i heard they work better with linux id choose nvidia the type depends on the budget