Will the host of A Virtual PC Get infected from the Virtual PC's virus?

I was wondering if a virus from a Virtual PC can infect the real computer. I would proabally use the Virtual PC if it doesen’t infect the real PC so if I acidently downloaded a virus, it woulden’t infect my computer with all my files. The version that I want to know about is 2007 SP1.

http://forum.avast.com/index.php?topic=44356.0

Thanks.