Why don't you just keep the PC you have now for netgammon. That would be much better than the toil and hard drive space use you'll suffer from installing two major operating systems on one relatively inexpensive computer (the Mini). Plus, lots of people seem to have problems with Boot Camp, including loss of data. And of course, who wants to disgrace a Mac with Windows.
If you already have a PC, what's the point? Are you planning on throwing it in the garbage?
Thats just what I would do... if I had a PC for some reason...