As another suggestion, you could try installing the Tomato firmware rather than dd-wrt. I used to run dd-wrt (on a v1.2 WRT-54GS) and had similar stability issues; I've personally found Tomato (http://www.polarcloud.com/tomato) to be more stable.
Nels Lindquist nlindq@maei.ca
+1 on tomato very stable, otherwise I would look to separate the wireless function from the router and run something like pfsense.