Just wanted to say problem solved. It's either the memory or the memory slot, I have one stick in right now, I played some WoW on high settings for a few hours last night and then overnight I had my PC do some pretty heavy video and audio encoding, I also used media player while encoding and it ran well, no real hiccups, but only having one gig of ram sucks, it is noticably slower but at least there have been no crashes.
I wonder why neither memtest could catch that? hmmmm...