I'm using two Netgear WNR-2000 routers as AP's, moving between points works fine and I only need to set up the network details once on any device - all I did was set them up with the same SSID and security settings, no WDS setup required. You've probably already done so, but try and put them in non-overlapping channels too (1,6,11), if you have a smartphone or laptop there are plenty of apps that'll let you see which channels are busy as you move around.
Doublecheck that your security settings (username, password, encryption) matched on all the AP's.