Some time ago, I built an "Enterprise" disk imaging system, the equivalent of Symantec's Ghost product, from Open Source components, hosted on FreeBSD. In the process I discovered the FreeBSD ports collection, an astoundingly huge set of applications managed as part of FreeBSD itself. I used a whole raft of stuff from the ports collection as test tools in an all-Windows environment, everything from collaboration (Twiki) to network analysis (ntop).
I was doing a lot of install/smoke testing, and the Frisbee disk imaging system was an important part of that work. I published an interview with Mike Hibler, Frisbee's lead developer, in the March 2005 issue of Better Software magazine.
I discussed the wider issues of hosting test tools on FreeBSD in a paper for the 2005 Pacific Northwest Software Quality Conference, and now that paper has been adapted as a FreeBSD White Paper.
Dru Lavigne, a noted FreeBSD evangelist and Open Source advocate not only helped me through the process of editing the White Paper, but was also kind enough to publish an interview with me about the paper, about software testing in general, and about why FreeBSD is an excellent platform for network testing tools.
I encourage you to read the White Paper and the interview, especially if you're involved in testing networked devices of any kind, especially if you're frustrated by the tools available on Windows for doing this sort of work.