Yeah, that's what I meant with "edition of 7". But according to this wiki page ("I" note under the compatibility table) you can sort of bypass this limitation:
http://en.wikipedia.org/wiki/Windows..._PC#endnote_I3
Though I do not understand how they manage to get it to install XP Sp3 as a virtual machine in Virtual PC with one of the lesser versions of 7. Maybe you could stubbornly try to download the files for the Professional version and install it anyway. Virtual PC 2007 wasn't supposed to work on my Vista Home Premium either, but it did. It just gave a meaningless 'thou shall not install' warning message when I installed it. The virtual machines didn't care it was a lesser edition of Vista.