DONT use a ASRock 775XFIRE-ESATA2 LGA775. It was the cheapest board with these specs on ebay except it wont boot with any AMD/ATI card I've put in it. Even booting with any nVidia card (all of which worked), I still cant even see any AMD/ATI cards connected on 1x or 16x.
It might just be my board, but for sure they are all really finicky about memory. Mine wont boot with two matched 1GB sticks, but will with one of them pulled out.
I've heard the ConRoe version of this same board will work but I haven't tried it myself.
Thanks for the feedback, that's good info to know. I was actually considering trying that board with an old Pentium D CPU I have lying around since it wouldn't work with my E5300, but looked more at the P45X3 since it has more 1x slots if I ever wanted to add several GPUs. Gonna have to do some digging to see how similar these boards are as far as chipset and bios.
EDIT: This is the board I am looking at:
http://3btech.net/asp4coqu16mo.html