iChat problems with a new iMac G5!

[Jazzmo]

I recently decided to try out the Isight system on my iMac G5. This machine is wirelessly connected to my linksys WRT54GSV4 router, as is my Windows HP laptop. They both work smoothly in every respect except that the G5 won't iChat properly.
I'm using Verizon's DSL modem a Westell Wirespeed 2100. It is bridged directly to the Linksys. I have no access to the Westell via a browser config page. I've tried a number of changes within the Linksys configuration pages via a browser. Some were suggested forwarding and triggering port changes but so far no success. I either get a "no response" or a 3 out of 4 point conversation with the recipient I try to reach. ie: (they can see (1) and hear (2) me and I can see (3) but NOT hear (4) them.
After extensive conversations with both Verizon and Linksys tech support staff, I'm still unable to resolve the incoming audio problem. I've checked all the audio settings on the G5 and everything there is as it should be.
Although I'm able to webcam successfully with my HP Laptop running a Logitech Orbit webcamera on MSN messenger, I'd really love to be able to take advantage of my iMac's iSight feature! Grandkids you know?

Any relevent advice would be greatly appreciated!!

Jim