I'm using 512 Ram and 1.3 vanilla RTW, and certainly have the same problem.

I notice that the temporary process someting like ~005temp can be seen in task manager, and when the "leak" is bad then you can get extra temporary processes started. These are associated with RTW because stopping them stops RTW!.

I must admit I've taken to a quick crash out of RTW using task manger stopping the temporary processes (or rtw.exe) .

And don't anyone bother telling me that stopping processes like that is bad for your computer. As long as you don't stop critical processes you are not going to get into trouble.