The problem may be the SiS chipset, you may need to upgrade the chipset drivers.
I've never been a fan of Sis chipsets, most of the time they are slower and with stability problems.
The P4S533 is a terrible performer. I'm not surprised at all that you couldn't use your radeon9700 at all.
An intel 845-E is a much better solution. Since you got a GeforceFx you may want to invest in a much better motherboard.
Sometimes I hate being right everytime.