I'm trying to crack my WPA router but I have a situation. My desktop's wireless card doesn't seem to work very well but my laptop is too slow. I have captured a couple of handshakes with the laptop which is a 2GHz single core but I want to run the crack on my desktop which is a 3.2GHz dual core. I tried copying the .cap file but Aircrack says no network selected. I thought I didn't need to be in contact with the router for the crack. Am I wrong?

Chris