A lot of people are using pairs of Linksys WAP11 access points to link wired networks. Linksys and its retail partners keep dropping the price, which was over $200 last summer and is now available for just $135 from Amazon.com. Amazon is also running a free slower shipping promotion for orders $99 and higher (with some qualifications: mainland U.S. only, etc.) for which Linksys equipment qualifies. The Linksys WMP11, their fully integrated PCI card with Windows XP drivers, is just $99.95; it squeaks in over the free-shipping cutoff.
Linksys continues to update its firmware and drivers for the WAP11. I just installed the latest 1.4i release on the pair that I and a neighbor use to link our offices.
Disclosure: those links above are affiliate links. Buy something via these links and I get a cut - and I thank you for it!