Hello,
I have the Airport Extreme Base Station (AEBS).
First off, the cable from Comcast comes from the wall, then to my Comcast modem, and then the ethernet cable to my AEBS.
Off of my AEBS i have my iMac connected wirelessly, my xBox wired directly, my LG HDTV wired directly, and we use our iPhones (x2) with varying frequency.
I do not own a PS3, btu there is no reason that your PS3 wouldn't work with your 'airport extreme wireless router' Im assuming thats the same device i have.
Every PS3 has an internal WiFi adapter, I however connect my xBox for the best speeds. The same reason with the HDTV. Those are the streaming devices for videos, shows, and gaming. The iMac has the least internet (data) workload so I leave that to WiFi.
for future reference, it helps when you have detailed info on your setup
hope that helps.