I think it was Skymtl that wrote a good thread here or on his site as to why tools like Afterburner are not good for recording memory use in games. Not sure if it was entirely due to the "game will take as much as is available" issue only, or if there were other reasons.

Maybe he'll chime in, but that is why I said that. If there are good tools to record memory use, I'll gladly retract.