Don't know where you get one from in the states, but here in Australia, I use a Shuttle XPC wireless network adapter (internal) with an external antenna.
See link:
http://global.shuttle.com/Product/Ac...ec.asp?A_id=34
I takes up one usb header on your board, so you won't have two ports at the front, but is very neat and fits just behind the rear panel on a morex case.