Your power supply sounds like it is fine because I had a 350 watt one and I ran more stuff on it than that.
I would check and see what tempurature your video card is running and check the driver for it.
I'm sad to say that I read the entire 42 pages of this thread.
But I am not sad to say is that I freaking want a headcrab. I might see if I can make one.
I got their first two and they are good. I haven't even heard anything of Planets because I figured that since they got a new singer, then the band would go downhill from there.