vista sharing connection

I installed a new gigabit Ethernet card in both my XP machine and the test machine with Vista on it the cards then go to a gigabit switch but the Vista machine still goes threw the 100 megabit switch when transferring files. So I tried to share the connection from my XP machine and put a cross over cable to connect them but Vista still sees the router and thinks it's connected to it instead of going directly from machine to machine? I tried resetting the IP address on the Vista machine but nothing I've done so far is working?
Thanks for any help, Rich