Question : Problem: What is WPA encryption?

I am using a BT voyager 2110 adsl wireless router and our wireless network uses 128bit WEP encryption with a encyption key. There is an option for WPA encryption which my manager has asked me to look into.

What does this do as far as security compared to 128bit WEP encryption?
What else needs to be configured for it to work?  

Answer : Problem: What is WPA encryption?

That is Wi-fi Protected Access, aka 802.11i.  

Here is a whole article on this topic, but I will extract the meat real quick:
http://support.microsoft.com/?kbid=815485

"WPA key management
With 802.1x, the rekeying of unicast encryption keys is optional. Additionally, 802.11 and 802.1x provide no mechanism to change the global encryption key used for multicast and broadcast traffic. With WPA, rekeying of both unicast and global encryption keys is required. For the unicast encryption key, the Temporal Key Integrity Protocol (TKIP) changes the key for every frame, and the change is synchronized between the wireless client and the wireless access point (AP). For the global encryption key, WPA includes a facility for the wireless AP to advertise the changed key to the connected wireless clients."

Basically it uses TKIP to replace WEP.  TKIP is much stronger.

All of your access points and client machines would have to be changed to implement WPA, and there will probably have to be some firmware updates and/or outright replacing some hardware.  Check with your manufacturer's website for details about if they support WPA.

BTW... If you use windows to handle your wireless connections, WPA is included in XP sp2.

Hope that helps!