New MBP 13" airport card slow??

Well just got my MBP yesterday... and i upgraded to snow leopard after installing coconut (not erase install just upgrade). For some reason my internet speed is extremely slow. i have a 15mbps connection at my house. between the MBP and router is around 20ft and one wall. i have a pc in the same location as the mbp and i get like 13mbps on my pc and <3mbps for mbp... tried configuring the airport settings but not working HELP!! frustrated... starting to suspect that the airport card is defective...

PS: the adapter card on my pc is from ebay and its doing better than the MBP??