Update: the trojan was obviously a false positive, since it didnt make a damn bit of difference.
So here's where we are:
It's not bad ram.
It's not a virus.
It's not any program I have running.
This leaves only one option, as heretical as it might be: Vista.
I don't like the thought of using Vista as a scapegoat like everyone else, but I'm really down to zero other possibilities at the moment. And if the problem really is Vista having a horrible, silly memory leak, then my only option is to format, which is really the one thing i didnt want to do, but suppose i'll have to do. The problem is, I'm not sure how to go about it. I've only heard of countless problems from people trying to downgrade from Vista to XP, and wanted to know if anyone here has done it successfully, and if so, how. Any help would be appreciated.