>> Virtual PC is free. No other advantage. > So is VMWare Server.
So is colinux, which is IMHO a perfect solution for this. colinux practically avoids virtualization overhead by not using virtualization at all by running a (modified) linux kernel as a win32 process. It can run as a service (so you can set it to auto-start). It may use a physical partition or a file-based block device. The only real question is -- a build server on a laptop? what's its average uptime? how well does the distributed build system work with servers that are not always online?
