I would steer clear of both of those types of wireless cards. I have had HORRIBLE experiences with the pci type, mainly because half of the signal has to travel through a metal case, which is almost certain to kill the signal almost completely on that side.
In my house I couldn't even have a computer across the hall from the router with one of those cards. I'm guessing usb dongles are similar.
It's not a big problem with internal laptop wireless cards because they have less metal to go through.
I would ditch both of those in favor of a good usb wirless module (the ones with a little antennta and a long cord)... you could mount it anywhere you need, just make it away from the computer.
Hope that helps.