How do i set up my PS3 for online play?

May be...

Ok heres the deal, I already have a cable modem, but its connected to the computer ~25-30 feet away from the console. I know theres 50ft ethernet cables, but thats too much of a pain. What I was thinking was buying a separate modem (the Motorola SB5120 for instance) and a router for the TV cable, then connect the cable to both the TV cable box (its comcast if thats matters) and modem, then connecting an Ethernet cable to the from the modem to the PS3. Are all cable modems compatable with the PS3 this way? and will this set up work?

i dont know

If u are to lazy to buy ethernet cable than you can use wlan built into the ps3 if you have a wireless router. Instructions can be found at playstation.com otherwise you must buy a long ethernet cable.

Just use the wi-fi that's built onto a PS3. Saves all the wire hassle, but you do need a router.

do not buy another modem. it's a waste of money and time. just use the built in wi-fi in the ps3 and get a router. i would recommend the linksys wireless g router. thats what i have and it works great with the ps3.

You should be able to buy a wired or wireless router for about $30. I can't remember if the PS3 has WiFi like the Wii but I have a wireless router and it was quick and easy to install and use.