WEP Encryption works in 2000 but not XP

We have just installed a Wireless Network, and the Access Point (Netgear ME102) works perfectly with Windows 2000 Clients using ME401 Cards.

However, when entering the exact same information into a Windows XP Client, the Client drops off the Network, i.e., with No WEP on the Access Point or the Client, the connection is established, but as soon as a WEP is entered, the XP Client can’t access it (a Windows 2000 Client works perfectly after entering the WEP).

I have spent hours trying everycombination, but I can’t get this to work with a WEP!

Does anyone know if this is a problem with XP or Netgear, and is there a way around it?!

Thanks for any assistance.