Question about Mac OS X, bootcamp, windows virus

I know pretty much nothing about OS X, so I have a question regarding a friends MAC.

Troy has a late model Mac and is using Leopard. Troy would like to use Bootcamp to run a few Windows based programs, I believe also that he will surf the web under Windows.

The question, which I cannot answer, is does Troy need to run a Windows based firewall/anti-virus in this configuration?

I also have a question that I believe will come up in time. Will Parrallels or VMware do a better job than bootcamp?