Well you can pick up a Linksys WRT54G (or WRT54G2) router on the cheap and run dd-wrt. That'll be a $10 solution.
Or for about $20US you can pick up a Cisco AIR-PI21AG-A-K9 802.11G PCI Wireless Adapter on eBay - not sure if its compatable with your version but it worked for me on 123 and on 2.0.
Those little Cisco adapters are cheap and really good in my (limited) experience.