Just bought an ASUS PCE-N13 PCI-e wireless card and the signal strength isn't as good as my old Linksys PCI card!
It uses two standard 4" or so screw-on antennae.
Is there some antenna setup I can buy that will screw on to the card with some cabling so I can locate the antenna further away from my desk?
More aboutbetter antennas internal card
Bear in mind that there are dramatic losses with a longer cable, but I'm sure you'll find something that fits your description on e-bay (or Google it -- there are companies which specialise in wifi antennas)