Is there any Windows software out there to help track down a memory leak in third-party software?

My System (C:/) partition is 300GB but in reality there is only about 130GB of data on it, however I have a massive memory leak to the tune of about a GB per day! The partition slowly fills up over about a six month period and eventually I get a BSOD, Windows reboots, and the partition drops back to only having 130GB on it again.

I've done some trial 'n error testing (running some programs and not others while watching the partition grow) and I have a very strong suspicion as to what software is causing this, but I won't name it here yet as I'm not 100% sure.

What I'm after then is some kind of software that can positively identify the memory leak, then I can go to the developers with the problem?

Can anyone suggest anything?