I have had excellent results using VM-Ware Fusion.  This runs almost
any operating system in a window on the MAC and requires no re-boot.
You can simultaneously run the MAC and the Windows programs.

I am using it to run a weather station in Windows XP while the MAC
runs a home-automation system.  When you plug in a peripheral, such
as a USB serial adapter, the program asks you if you want to use it
in MAC or Windows.

You can use VM-Ware Fusion for 30 days as a free trial, then it costs
about $50 US.  See  http://www.vmware.com/products/fusion/ 

Hank Walters