My Long Tail site gets linked to by Scripting News, and my server starts acting up.  It's done this a couple of times before (before the ram upgrade as well), simply locking up for no apparent reason.  No blue screen, just a hung system. 

Maybe one of the old RAM sticks is iffy, and adding the new ram made the problem worse.  If it keeps happening, I'll remove the two 128mb DIMMs and just leave the new 512mb one.