yesterday i bought a 360 pro and a copy of GTA IV. i've played a little on the TV in my living room, but i'm planning on running the system off of my monitor, which supports DVI input. i run the 360 signal into my monitor via a HDMI/DVI cable, but this leaves me with no sound while i play. is there any way i can use my headphones here, or do i have to go get speakers or something? i'd really appreciate any advice, as i'm a bit of an A/V newbie.