No, dont enable that ATA-66 override, its not needed.
To get your Radeon to work you need the nVidia AGPGART patch. I dont use it since I have a GF4 card, but look through this forum and I bet you can get info on how to get it to work.
If you do a "cat /proc/pci" you can see what chipset your network card is using. Note it down and enable support for it in the kernel network config.
"Never bump a baby carriage out of a crosswalk unless the kid's really asking for it."