I use a Linksys WRT54G and it works perfect. It's a 1st generation one infact. This site has helped me a bit with it:
Although, you need to be extremely careful when you're upgrading the firmware on it, which this will do. It's a lengthy process and if done wrong will "brick" your router. And, "brick"ing your router does exactly what it sounds like.. Lol...
If you're not 100% confident and have done firmware upgrades before... You may want to ignore this post. Otherwise, it really did help mine out quite a bit. Nothing like going with an OpenSource linux based firmware over the factory firmware on it.