Confounding Network Hardware Upgrade Issue

[1sounder]

I've got an existing network config that I'd like to upgrade, but I'm running into some strange problems.

Current hardware:

Modem/Router: Netopia Cayman 3346 (I.P. ...1.254)
Router: Linksys WRT54G (config as static)
2 APs: Linksys WAP54G

1 Macbook Pro
1 Dell running XP (w/VPN config)

The config of the above is:

Modem/Router LAN out goes to WAN in of WRT54G
WRT54G is configured as a Static IP (I.P.: .207.138)
APs hardwire to LAN
BUT, all ports of modem/router are being used as well as all ports of WRT54G (total of 8)

Updated Hardware - Replaced With:

WRT54G with Dlink DIR-628 wireless router
(DHCP inactive. Modem/router LAN port out to Dlink LAN in (Did NOT use static settings as above nor did I connect via WAN. Went from modem/router in LAN in of Dlink router).
Dlink I.P.: .0.1
SSID: kelp1
Channel: Mixed

Replaced 1 WRT with a Dlink DIR-628 router configured as an AP (DHCP not active)
Changed to static I.P.: .0.2
SSID: kelp1
Channel: Mixed

Replaced 1 WRT with Dlink DAP-1522 AP
Changed static to I.P.: .0.52
SSID: kelp1
Channel: Mixed

Situation after change:

Configured all the changes above with Macbook Pro. My macbook pro had great signal - no problems connecting.

iPhone picked up all wireless signals as well - no problems connecting.

Power cycled all devises and all came back up and everything worked great.

Problem:

The existing computers in the home would not connect to the wireless network. I did all the usual ipconfig/release, ipconfig/renew. Confirmed wireless switches on, etc. - nothing.

The Mac would not connect via wired or wireless and said: "Self Assigned IP" and would show a full signal, but would not connect. Called AppleCare and they couldn't figure that one out either.

At the end of the day re-connected all the old G gear and everything connected properly...

Thoughts:

Might it have something to do with using and then not using the WAN on the new Dlink as well as not setting a static on that devise?

Seems strange that my computer and iphone connect to all APs with no problem, yet the computers that existed in the home prior to the upgrade do not....

As always - I appreciate your input.