Curt, a moderator over at Mark Minasi’s Reader Forum has a post on how he used GP in a Virtual PC to create an identical test environment of an existing GP server. The post is a bit technical but for the Admin’s among the group, it’s another test server option for you.
GP on a VPC
Archived post from 2007. Dynamics GP and the links it points to have changed since; check current documentation before relying on version-specific steps.