Your best bet is to hope that your computer has either VGA (the port an old monitor hooks up with, a newer one uses DVI, but there are DVI to VGA converters) or S-Video out. If so, you can hook that up to your TV.
If your computer only has one port, you can unhook your monitor for the game, using your TV as your monitor. You will need a 3.5mm to RCA for your audio with either S-video or VGA.
I am not familiar with HDMI on this matter. I only have a GForce 8800GT card that I bought about two years ago, it does not have HDMI. I know that audio can run with HDMI, but I do not know if cards with HDMI support audio or you if it is separate from the sound card. I guess it would depend on your setup.
But I'm a Windows guy, hate the Mac. But since Macs are much more unified than PC's, especially home-built ones like mine, let the guy at Best Buy or wherever you go know what kind of computer and TV that you have (model numbers). They should be able to help you out as long as you know what kind of inputs/outputs you have.
But like others said, if you have a video game console capable of ESPN3 streaming, that would definitely be the easiest solution for you.