If you're going WRT54G I'd lean towards using tomato, it's a little more streamlined and a tad bit more efficient.

I'm not a big fan of the RTNC utilized with these devices, they're more for the home-brew audience. The Ubiquiti NS is more of a pro device that's self-contained and has pretty good support, IT should also easily tap it's 10/100 port (which is pretty damn fast, imho)