I would like to display my desktop computer screen on my philips flatscreen monitor so i can enjoy my pc?

i have been trying to run my laptop thru my tv monitor...i tried the s-video cable with no luck i do not have the attachment thats used on the desktop computer on my tv or i would try that....subject matter experts(so-called) from best buy and circuit city told me to purchase an s-video cable but it doesnt work ...can someone please tell me what i can do to view my laptop thru my tv monitor...thanx...tony