1. Check the HCL
here at LQ to find a well supported wireless card.
2. If there is no guides in the entry for that wireless card, google it.
3. If you still haven't found a guide, post once you have a wireless card so we can talk you through the steps.
__ EDIT ___
VERY important. Check the version numbers on the wireless card. They are very important. If everyone says v3 is great, make sure the box says version3. If you need to, have the moron at bestbuy open the box up.