Was able to disable NAT and am still having the same issue.   The Ipad sees the router, asks for the passphrase, I enter it in, it tries to join the network, then kicks me out after a couple seconds and tells me it is unable to join the network.   I suppose for the next step I will try to turn off the 2wire wireless and run all the wireless from the upstairs WRT and see if that works for me.  Otherwise I am about to just fork over the $100 for an actual access point after I get done dislodging this router from my my computer screen.