Go to your control panel and open "Network Connections".
There, right click your "Ethernet adapter Local Area Connection" and select "properties"
In the small list, scroll down to "TCP/IP" and double click.
Then instead of assigning it automatically set it manually with the following settings.
IPv4 Address 192.168.1.41
Subnet Mask 255.255.255.0
Default Gateway 192.168.1.1
This could be slightly different as you have vista (right?).
If this is way off and you can't find it I'll find a guide. (this was from the top of my head.)