I've noticed that my wifi speed on my 2009 5.1 Mac Pro is about half or even sometimes less than my other wifi devices. The RSSI: is -79 dBm and the Noise: is -90dBm. Ive read that these are not ideal numbers for good wifi. I did remove the original wifi card a while to try using a combo wifi/BT 4.0 card off of eBAY. I think I have the original wifi card connected back up properly but maybe not. I do have the option of running an ethernet cable from the adjoining room through the drywall as my Mac Pro pretty much stays put. Maybe this would be better?