Well, first of all, S-Video will get u a **** picture. If it's a old tv I suppose that's the only solution, but if it's HD, then you need either a DVI to DVI or DVI to HDMI, check what the tv has. And I'm not sure, but I doubt you can force the 16:9 unless you play with your resolutions. Now if the tv can do it automatically (through some display setting)... then it's another story.
I have an LG lcd, and have both inputs dvi and hdmi... BUT it says that true hd can only be achieved by hdmi on my particular tv. So make sure you know what ur tv supports as far as resolution goes for those connections.