Usually tv-out on a video card is in the form of s-video (SVHS), but some are in the form of RCA out.
If you only have RCA in on your tv, and your vid card has s-video, then you need a converter cable which usually comes with your video card when you purchase it (a small cable that is s-video male on one end and RCA female on the other end). If your tv has S-video in and your card has S-video out, then you have nothing to worry about, just get a good quality S-video cable and enjoy!