Not a bad deal. The 501 is a decent little unit. We actually used it in a production environment shortly for a company of roughly 500+ employees until we got our 515Es back up.
Also has the ability to tie in with several content filtering servers - we had ours tied to Websense.
ya its a good unit i upgraded our company to 4 linksys(cisco) routers to segregate traffic. we ran a large ecommerce b2b site on it but we started running into bandwidth issues w/ the amount of internal/external traffic it was overloaded.