I found a great article on the MSDN website that discussed how to identify and prevent memory leaks in managed code. There's certainly a wealth of information available there, including how to use perfmon to actually find what type of leak you have, before you start going further.
I've run a memory profiler before, but I end up looking at it like a monkey trying to do a math problem. I'm not sure how to interpret the information presented to me.
I realize that this is a space that I know very little about, and therefore ask you, kind reader, to point me towards tools/techniques/documentation that I can use to become more proficient at solving performance types of problems.