Try changing the channel in use. Default is often 11, try something quite different.
Siting of the router is critical. It's very easy to get interference. Brick walls and the like will also have an effect on the range.
I'd doubt that Belkin or any other wireless make would make a great deal of difference. However external aerials may improve the signal quality (but lappys with built in wireless don't have those so I don't really know