How do I set a Wireless card to be my deafault card for the internet?

I have a PC that has a wired NIC and a wireless NIC in it. The wired NIC is used to access a Misys mainframe and the wireless NIC is used to access the internet. I need to find some way to tell windows XP SP2 to use the wireless NIC for the internet because it trys to use the wired card by default if it is not disabled.