I need to get LIVE going.

I bought a 50ft ethernet cable, i plugged it into my 360 and into my desktop tower. my tower has two internet jacks (we will call them). One is occupied by a ethernet cable that runs to my house router (which has no empty ports.

I used to get live by hooking in the ethernet into my laptop and using the wireless signal, but its a hassle so i do this instead

but its not working. I figured my tower would feed out the internet via the ethernet port - clearly doesnt. do i need to configure something?