I suspect you don't need a new router, just an antenna.  You could put a directional gain antenna on the router or your wireless card (if it has an external antenna connection) and focus your signal. Take a glance at this discussion, it might help:  http://talk.newagtalk.com/forums/thread-view.asp?tid=162568

I used one similar to this.  We used the antenna shown to get good service in the shop where we did not have enough signal to be usable.

I see ads for antennas promising up to 2 miles of range.  There is probably a lot of fine print in their promise.