I have an odd issue with a Netgear WIFI router, 4 computers, 2 pc laptops with XP and 7 installed, one MacBook Pro and one older Mac mini.
With security off everything can connect to the wifi.
With WPA-Security on only the Macs can connect to the wifi.
I've reset the Netgear router, done everything again from scratch, no deal. The PCs just can't connect. One of the laptops can connect to another Netgear router in a different location. The PCs can connect to other wifi networks just fine so the laptop PC hardware is fine.