Click Here Its a good article that teaches you how to increase your speed and bandwidth. Check it out.
I've already tried this on a WRT54G. It's nice that this model runs a Linux and allows you to install different firmware.
I have this installed on my router as of this past week, and I am happy so far, and I haven't even touched any of the features.
Awesome Thanks a lot for posting this article. It has actually saved me a bit of time at work. We had a pc about 35 ft away from a WRT54G, but blocked by 2 walls and the connection speed was "low/non-existant". I was just going to send a cat5 cable through the ceiling, but now we get a "good/very good" connection (FYI: I up-ed the signal strength to 95mW and the router is noticeably warmer... I'll probably lower it to 70mW as recommended in the article and hope that the signal strength doesn't suffer too much). I'm gonna do the same to my router at home! Woohoo!