First off,the best thing to try is leave XFdrake out of it:)j/k You could either edit the section that has the card to include some options to nudge it in the right direction..
BusID "PCI:0:14:0" #this is mine yours is probably not this...
ChipID "0x5159" #this is also mine....Radeon 7000 QY 64mb PCI
heres the best one yet...
Option "ForcePCIMode" "true"
I had that vbios problem with my trident onboard....it seems the radeon and trident take the same memory resources...so you might want to make sure that nothing conflicts....if that helps let me know,we'll do DRI enabling:)
Chuck