I already wrote a little about new, Windows 7, edition of Virtual PC. I was mostly satisfied with changes but I did notice that it was quite simplified.
Unfortunately one of things that was removed was support for operating systems different. Naive version of me though that this was due fact that Virtual PC is compatible with them out-of-box. I was wrong.
While in good old Virtual PC 2007 SP1 you got asked upon creating of virtual machine whether you want to use Windows or "Other" inside of it, that question is gone now. And while I could install FreeNAS in Virtual PC 2007, there is no way of installing it in new Virtual PC. Installation just hangs.
I cannot say that this is purely Microsoft's fault since FreeBSD has few issues with hardware handling itself, but it is very annoying when something that worked before just stops working. Even worst, code that handles FreeNAS is probably still somewhere deep inside of Virtual PC. It is purely design decision that caused it not to be accessible from user interface.
While on real systems I use Hyper-V Server for running *nix-like thingies (and that works great), that is not real option (since it does not exist) for testing on my laptop machine with Windows 7. On it I am currently playing with VirtualBox. This tool does have unsure future (Oracle-Sun trading) and sometimes I need to go to command line to accomplish simple things (VHD support), but it does allow me to install whichever OS I want.