Make sure you get the Linksys router ending with L, the WRT54G doesn't have as much memory as the WRT54GL on the newer hardware editions, and I think a different chipset.
Not an issue by itself, but custom firmwares are much more stable. I personally much prefer Tomato vs DD-WRT. Easy to install, not much customizing needed, but it is available. Also has neat usage statistics on the admin console, plus tons of advanced features if you ever want them (SSH, DDNS forwarding, QoS, etc.)
Tomato Firmware | polarcloud.com
edit: For home use, wireless N isn't really a huge deal unless you're always copying huge files. G is enough for media streaming, and much faster than your internet connection is going to be for the next 10 years unless you live in South Korea.