virtualbox.org

I'm working on a new pc running windows 7 64bit and realized that a couple of pieces of older software wont run on it so I set up an XP 32bit pc in virtualbox. This virtual pc will not be used much and mostly for internal things so the majority of the time it wont be on the internet but I can see a user either accidentally using the XP explorer thinking he or she is on the main PC or needing a image from the net for one of the programs that has to be run on the XP pc so using the XP explorer rather than the Windows 7 explorer. I have Microsoft essentials on both the host and the virtual PC but it seems like it bogs down the virtual PC a bit so I was wondering if anyone has set up a host as a proxy server for a guest and if so would that at least scan incoming internet data streams for viruses? I'm thinking that if it did I could remove the virtual PCs copy if Essentials and just let the host handle the incoming data stream. I realize that if someone intentionally downloads a virus it will get through but I can live with that rarity.

Suggestions?

http://windows.microsoft.com/en-us/wind ... on-Sharing
But the host will more than likely *not* scan the stream IMO.