Windows 7: Bandwidth Battle

Ok so my problem is that I have 2 desktops connected to my router. On this PC (1) I can open several online games at once without lag and without lagging the second machine at all. But as soon as you open a web page or anything on the second machine this one lags right out. I mean seriously facebook should not lag me on a 15mbit connection...

So basically if I am playing a game and my wife opens facebook I lag to the point the game freezes completely.

I have both machines connected to my router using cat6 cable since both of them use a gigabit adapter and the router also supports gigabit. I use a dlink dgl 4500n router. My bandwidth is 15 down 5 up.

Both machines are running Windows 7 ultimate (x64 on this one and x86 on the other)



Any ideas what could be lagging me out? You wouldn't think I would have this issue with a good cable connection and a good router.

What kind of router do you have?