I have a Dell Dimension 1100 B110 desktop and am wondering if a video card is available to be able to connect to other video sources (S connector or 75ohm cable)?

Needs a PCI card with TV out or a capture card

Do you mean connecting the output to another display device, or connecting things like a video to your PC? If it's the former, then...

By the looks of it, your motherboard does not have a graphics card slot; the only type of card you can install is a PCI card that has TV-Out (S-Video and composite). Unfortunately, this type of card might be hard to come by. Might have to look on eBay.

You could try one of these types of PC-to-TV devices instead:

http://www.av-cables.net/switch_boxes/pc-to-tv-27387.html

If it's the latter, then you need to get a PCI-based video capture card (not a video card) or an external USB video capture device that has the support for the inputs you require. Something like this:

http://www.snazzi.com/vc300.asp

Hope this helps.