After connecting your vista machine to your router it may not get the ip address from your DHCP server in this case this tutorial will help you to fix this issue.
Consider the following scenario
• You connect a Windows Vista-based computer to a network.
• A router or other device that is configured as a Dynamic Host Configuration Protocol (DHCP) server is configured on the network.
• The router or the other device does not support the DHCP BROADCAST flag.
In this scenario, Windows Vista cannot obtain an IP address.