Ben, you could go for an N range router and I've seen on Novatech the belkin N router F5D8231uk + F5D8051 (
http://www.novatech.co.uk/novatech/s....html?B5DUK061) which is an alright piece of kit.
but my personal preference goes to NOT using USB adapters for wlan as usb isnt always as reliable as PCI or even PCI Express.