Caution about using PCI. If you have the tower located in one of those computer desks that is blocked off on at least two sides, especially if the back of the tower is facing a wall, you can get a dead spot behind your computer desk where an attached antenna is. I've seen this a few times now (including with my own computer desk, which is backed against a wall). I connected one of those antennas with the cable extension, to get the antenna out of that dead space, and it hugely improved the signal.
Oops, I just noticed the Edimax adapter comes with one of those extender dealios with cable, not a direct-attached antenna.