Cisco 1240AG + HP IPAQ 2490B = Connection problems

To accompany our move to SIMS.NET and Lesson Monitor, SLT want PE to have PDA's for registering students in awkward places...

We have purchased some Cisco 1240AG wireless access points and HP IPAQ 2490b PDA's to do the registrations with.
I got hold of this kit after a recommendation form another NM that had it working.
However i cannot get the PDA's to associate with the AP, I can get laptops to work fine no problems.
I am trying it first of all with open authentication with a simple 120 bit WEP key to no avail. On the PDA it finds the SSID and trys to connect but doesn’t and just says 'Available' on the PDA.
The PDA connects fine using a WPA key to one of our other Netgear AP's - ruling out a faulty PDA.

Is there a setting on the AP of the PDA that anyone knows of to enable them to talk to each other?

Try re-setting the factory settings on the AP and start again. What software is the PDA running on?

AP has been completely reset with testing various aspects.
PDA is running Windows Mobile Version 5.0