While many use Sun's VirtualBox, an alternate solution is Virtual PC by Microsoft. With Virtual PC, there are many options available and the software is loaded with features. Like Sun's VirtualBox, Virtual PC offers an 'other' operating system option to install operating systems not listed.
After successful tests of Windows 7 Beta on VirtualBox, I decided to set it up on Virtual PC. As one can see in the pictures below, Virtual PC offers several dozen options but still falls short of VirtualBox. The setup of Windows 7 (see the screenshots in the last section of this article) is virtually the same as VirtualBox's setup. The lack of a tabbed interface, USB support, and Remote Connection makes Virtual PC 2007 less desirable.