I had a lot of trouble recently with VS2010 hammering my dev workstation. It was pretty complicated actually - when running VS I was getting way too much disk IO which was making my system almost unusable - even when just having a few editor tabs open in VS.
The problem seems to be that I had only 2GB of RAM in the box (blame someone else, I didn't provision it), and while VS wasn't really using much itself, it was spawning a whole lot of threads which were processing in the background (IntelliSense and so forth), modifying lots of memory, and because my RAM was semi-full the changed memory was getting written out to the swap file constantly. And then of course the virus scanner was going nuts looking at all the disk IO. The disk IO became the system bottleneck and brought the system to its knees when it wasn't even doing any useful work.
Adding a gig of RAM completely fixed it. Even though my system wasn't exactly running out of RAM, the extra head room stopped it from thrashing the disk all the time for trivial writes. FYI, the system resources page was showing 1GB 'in use' and the other GB full of 'cached, just in case you want it again' when I was having the trouble to start with, which initially made me think that RAM wasn't the problem.