|You can use performance monitor to view all sorts of data. It might give a clue as to what is going on.|
Wireless just takes a lot of processor some times. Both encryption and data work tasks the processor. The external may be causing some more load on the cpu and the usb would be my guess.
They make all sorts of wireless cards. Usb, pcmcia, expresscard, compact flash, pci, pci-e and others that might be tried. You can try a cheap usb if you think yours is at fault. They don't cost too much.
1/3 of highway deaths are caused by drunks. The rest are by people who can't drive any better than a drunk.