Can Only Access BIOS

I dug around some before posting, but I couldn't find anyone having the same problem as me, and I'm hoping this is the most appropriate forum. I apologize for the length, but I wanted to post everything I thought might be pertinent. I was playing Guild Wars when my GeForce 4 Ti4400 died. I got a working Radeon 9700 from a friend (he was using it up until the moment I got it, and I ran AquaMark 3D on it) and ran into only a billion problems. When I performed certain actions involving the online video game Guild Wars, my computer would suddenly reboot with no warning. I adjusted "reboot on error" in the system properties. It no longer rebooted, but instead, I got a solid blue screen (no words, just a blue screen), and I had to hold the power switch down to turn off the system. I suspect that troubleshooting this BSoD problem and putting my system through that repeatedly probably messed up some settings or something. The last thing I did to my computer was install the ATI Catalyst 7.8 display driver only (I was testing out the various driver releases one-by-one to see if any of them fixed my BSoD problem). It installed, asked me if I wanted to restart, I clicked yes, it began restarting, froze at a black screen (not the first time I had that problem since all my video card/Guild Wars problems), I once again held the power switch down to turn it off, waited a few seconds to turn it back on, and since then I have had the error described under the "Current Problem" heading above.