BAD RAM?

My friends PC is home built, and the other day his trial account of Win7 ended so I was going to give him XP, he wanted it, dont ask...
When we tried to install XP, it would get to the part where it reboots and then start completely over from the beginning.
When I tried again with Windows 7, it would copy files to 100%, but get stuck at Expanding them on 0% for about 10 minutes then say that there was an error reading the disc...
I tried the old standby, of removing all but the closest DIMM to the cpu, and took out the vid card. POOF, it worked like magic.
So I got Windows 7 installed again, put the video card and ram back and, epic fail. the machine would not boot. I took out one DIMM (the far one) and it worked again. I put that stick (the suspicious one) into the main slot and it did not work. wouldnt boot at all.
My friend says that his ram was fine before the trial account ended, so my question is this :

Would the mobo's bios get upset that I installed windows with 1 stick and not accept adding another? Or do you guys think the RAM is just a bad stick?
Or is there something I can do in BIOS after installing with 1 gig to make it take more RAM? keep in mind it runs on one stick, but not the other. They are identical 1gb GSkill sticks.
Thanks in Advance,
Absynth

It sounds like bad RAM to me.

I agree. It sounds like a bad stick of RAM to me. You said that you tried the suspicious stick by itself in the main slot (where the other one worked by itself) and it would not boot?

If that's the case, then somehow my guess is that the suspicious stick of RAM is bad.