I don't know what you budget is for this project, but I would not be surprised if this exceeded it. I am going to provide the information anyway though, just in case! There is a company called Gefen who makes great products for video in the pro-sumer to professional range. The product I would recommend is the Gefen VGA to DVI Scaler PLUS, the MSRP is $329USD, but I imagine you could find it cheaper elsewher. The product takes VGA in scales it and outputs DVI. This is important because you cannot simply adapt VGA to DVI or HDMI, it must be scaled up in order to match the resolution of your display. Gefen also makes a DVI to HDMI adapter (www.gefen.com/kvm/dvi-hdmi-adapters.jsp (Sorry I cn only post one hyperlink as a new user)) (so do other companies, but I really like this one) if your TV does not support DVI, or if you would just prefer HDMI. I'm sure there are other hardware solutions out there that would work for what you are looking for, but this is the only device that I have had personal experience with, and therefore is the only one I am comfortable recommending.
Another option is to go with a USB external video card that supports DVI. The advantage to this is that it will allows support for a wider variety of resolutions. The solution I suggested above should work even on a low end video card, but there is still a chance that you will not be able to get 16:9 out of it.
Good luck!
Also, as many others have suggested, stay away from S-Video if you can. It is a horrible format and I really wish it would just go away.
It's funny this answer was not voted up more, but that's the best answer. A simple adapter didn't do the trick, as so well explained by @Saavedro. I need a converter box. I'll probably look for some video streaming box instead. Thank you all! – Martin Plante – 2009-07-30T14:26:57.183
Yeah, I learned all this myself the hard way when I got my TV ;) – Saavedro – 2009-08-02T05:38:32.343
Would a simple VGA-HDMI adapter work, given I can make my video card do high resolutions? I have a VGA-DVI and a DVI-HDMI adapter, but when combined, they don't fit in the narrow space between the input and the stand :( so I couldn't test this. – Martin Plante – 2009-07-21T00:28:48.053
Unfortunately no. DVI has pins that allow an analog (VGA) signal to be output, and that is what a VGA-DVI adapter uses. HDMI can -only- carry a digital signal, so there will not be any picture. – Saavedro – 2009-07-21T13:50:28.413