Does that cable work with your XBox or are you using a different cable for the Xbox? If the cable works with your XBox and not the PS2, maybe the PS2 connector is bad. I know this is a dumb suggestion, but ya never know: did you connect the red video plug into the video port on the back of your tv? There are 2 reds - one is for audio. If that isn't the problem, then I would have to say it's either a setting (which you might have already addressed) or a bad cable. Are you sure the cable is plugged all the way into your PS2? Sometimes the cable feels like it's in, but it's only halfway in and not making a good connection.
By the way, did your BestBuy have a real long line because only 3 of the 12 registers were open? Poor planning on the part of the manager or BestBuy conspiracy to get you to stay in the store longer and buy impulse items? "Oooh look - It's "Tango and Cash" on sale for 12.99! If I wasn't standing here waiting, I would have never noticed it..." I hate Best Buy! At least they don't check my bag and receipt like I'm being accused of stealing every time I BUY something there anymore. "Why do you need to check my receipt? I'm a big boy, I know how to read numbers! Shouldn't you be working one of the empty registers instead of harassing me about my receipt?" #%@$@Best Buy!!