i use a linksys pci adapter with a d-link antenna. it works great for me. any 7dbi antenna will work. if you put your pc under the desk the pci wireless adapter will not have good reception.
this is the antenna i use Micro Center - D-Link ANT24-0700 2.4 GHz Omni-Directional 7dBi Indoor Antenna
you can find them on ebay cheaper
