I have a new D-Link DIR-655 that I've been trying to set-up all day to connect to the internet (which needs to be a PPPoA connection) through my old Netgear DG834G. No matter what I try, I cannot get the former online.
You may have already tried this, but check out the respective support sites. I did this a few years ago with Linksys routers and there was a definite sequence of steps you had to use to get them both to work, particularly the wireless.