what wireless card do you have?
if its a B card some manufactures are releasing firmware updates for WPA. but not all
Winxp has released a patch for WPA, might want to give that a whirl.
as for secuirty about 99.9% of people who see a wireless network have WEP they pass right by it unless you have something they seriously want. Enable mac filtering, Disable SSID and limit how many ip addresses your router gives out and you will have a pretty secure set up for a wireless home network
also i suggest to update to the newest firmware for the router, the new slick cisco interface rocks