Didn't know where to post this and as this is one of the bettier forum I know...here it is. I've installed Vista on two machines that are connected via a Belkin router and Lynksys 5 port hub. My problem is that whenever I am transferring files from one machine to the other, my Internet connection just about comes to a stand still. Never had a problem like this before. Any thoughts or comments as what could be the problem/fix?

As Leo has already stated.

Try using a switch instead of a hub. A switch is more efficient at packet management than a hub is.  The symptons in which you are describing (assuming you have a hub and not a switch) is how a hub is designed to handle packets. The packets will be broadcasted to every port the router is connected to.

If you are using a switch and not a hub, then this solution has nothing to do with your problem.

As "Vista" being an issue, I personally have not seen much degradation in network perfomance. I have been running/testing Vista for over 1 1/2 years on over 100 pc/laptops across multiple Vlans across a WAN. The biggest issue I have had is the initial negotiation of the connection this is mostly attributed to Vista's firewall.