I already have Win 7 on an internal Bootcamp drive. It so far has worked well, Bootcamp performance drag is minimal, if at all. Now I want to install Win Server 2008 R2 and load a bunch of virtuals using Hyper-V Manager. The virtuals are already created. This is to practice for a certification test....
Running Mountain Lion, 2010 MP 2 X 2.4 (8 core) 24 GB RAM, all HDD slots full.
Mac Pro, Mac OS X (10.7), 2.4 8 core, MBP, MBA, yadda yadda
Works like a charm. Apple Supports says you can have multiple instances of Bootcamp. Win Server 2008 R2 is up and running, drivers installed (except issues with Bluetooth) and accepting Windows Updates and Service Packs.