Two more tool suggestions.
Luke Stackwalker has a cute name (even if it's trying a bit hard for my taste), it won't cost you anything, and you get the source code. It claims to support multi threaded programs, too. So it is surely worth a spin.
http://lukestackwalker.sourceforge.net/
Also Glowcode, which I've had pointed out to me as worth using:
Unfortunately I haven't done any PC work for a while, so I haven't tried either of these. I hope the suggestions are of help anyway.
