Vista is stupid. The connection manager should never say it has access to the access point if it doesn't have an ip address. Fact is, the router is blocking it for some reason, either due to incompatible security or transmission modes, you have DHCP disabled, you have a static ip set for the adapters, your DHCP scope is too short, therefore it cannot assign anymore ip addresses.
Check all those first.
I looked at the model you have and it supports a maximum security mode of WPA AES. Disable mixed modes, since it's going to drop all the connections to that anyways.
Also, see if they will connect with no security first.
As well, in some instances, your firewall could be blocking the communication. I have ran into this too many problems with Norton, Zone Alarm, and McAfee throughout my tech calls.