Get the Buffalo WLICBG54S
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" A good deal at $42 from Amazon, with free shipping.
However, beware of the limitations of using an external antenna. The antenna must be very close to the notebook. If you use an extension cable, you will lose a lot of the gain.
You may want to consider the external wireless access points from Buffalo. The USB 2.0 and Ethernet models can at least be placed closer to where you want the antenna, even an outdoor antenna (you can use a longer Ethernet cable (100 meters) than a USB 2.0 cable (16'), though the disadvantage is that you have to run power to the Ethernet access point, and the Ethernet access point is more expensive.
Ethernet access point: "
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" USB access point "
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" Not to nit-pick, but it's CardBus, not PCMCIA, unless you have a very, very old laptop.