Thanks Guys!!

Rostoons,
I'm using the cMuscle system. It uses NURBS muscles with a proprietary skin deformer that allows you to not only do muscles that stretch and squash but also you can get the skin to slide over the muscles or bones. It has jiggle settings and a bunch of ofher stuff. Best $250 I ever spent.

Magget 78,
The muscles are NURBS, not polys so they are very light. There really is no reason to consdier displacement maps or anything like that since the muscles are under the skin and don't require any real detail..

Jay,
I took a look at muscleTK but the cMuscle system looked better to me so I went with it. The first thing I did was print out instructions which took some time since it doesn't come with a printable manual. The instructions are in HTML format so I had to go to each page and print it seperately. Over all, the system is pretty easy to use. It allows you to mirror bind weights and muscles too which saves a lot of time.