Ok, I have an ASUS A7N266-VM (nForce 1 based MoBo) and am upgrading it with a Radeon 9600 Pro. Do I have to reinstall Windows? I know I would have to if I was previosly using a discrete Nvidia graphics card, but the onboard on runs on the same drivers as the MoBo (obviosly) I'm guessing no, but if anyone knows for sure make sure to let me know. Pease I appreciate it.
No, you do not have to reinstall windows. You will however have to go into the motherboards BIOS and disable the onboard video.
A good method would be to unistall the onboard video drivers and then shutdown the computer. Install the new video card, go into BIOS and disable the onboard video and then boot into windows. windows should pick up the new card and then you can install the latest CAT 3.8 drivers for your 9600.