Vista won't connect to secure wireless network

Have a CompUSA (FSI) wireless router running WPA (TKIP) w/ passphrase. Works
great on several XP Pro machines. Just purchased a Gateway MX3705 w/ Vista
Home Premium. It finds the network but will not connect, and when I
"diagnose" the problem it says it failed for "an unknown reason." There is an
un-secured network in my neighborhood, and the computer can connect fine to
this, so I think the card is OK.

Things I've tried:

-Removing security from our wireless network. Still wouldn't connect.
-Changing mode from "AP" to "ad-hoc". Connected! But my wired machines would
not connect, and it still wouldn't allow any kind of security.

Any ideas?