Upgraded desktop computers, now wireless laptops can't connect

Last week I had a Win XP desktop computer. I use a Netgear WGR614 V6 router. I have fiber to the house and use a Cat5e Ethernet cable to connect the router to the wall jack and Cat5e from the router to the XP computer. I also used Wi-Fi to connect my Win7 x64 new laptop and an older XP laptop to the Internet. Everyone was happy and all worked well!

I set-up a new Dell Win7 x64 desktop computer (it currently connects to the Internet just fine).

During the period I was setting up the new Win7 desktop I had both the XP desktop unit AND the new Win7 desktop connected to the router via Ethernet cables (at that time both laptops could connect to the Internet). After I had transferred the XP files to the Win 7 computer I just shut down the XP computer and removed the Ethernet cable linking the XP computer and the router - the new Win7 computer still connected to the Internet fine (as it still does today).

I made 2 changes to the router:
1) I had the XP desktop connected to Port 3 on the back of the router and had the Win7 x64 desktop connected to Port 2 on the router.
2) I used Cat5e cable on the XP desktop and used a Cat 6 cable to connect the new Win7 desktop unit to the router.

Problem - both laptops see my router name but neither laptop can connect - even ran the troubleshooting routine (no help).

Could simply using Cat6 cable be causing a problem (Win7 desktop connects fine via the cable, laptops can not connect via Wi-Fi)? Surely just changing the port I connect the desktop cable to the router with wouldn't cause any problem would it?

Do I need to do some sort of set-up or configuration to the new desktop unit to make the router Wi-Fi work for the laptops ??

Robert