Hi
Steve, you don't say what sort of camera you are using so it is a little difficult to advise on what software to use, there are a number of free one's around but whether your camera is supported or not is the question.
MD, your signature say's you have a 400D, DSLRFocus quite clearly say on their website that the 400D is NOT supported although I have heard of a workaround. I use a 350D and use ImagesPlus, this program has support for the 400D, there are other programs around with 400D support but I cannot comment on them as I only use ImagesPlus now for focus, image aquisition and processing.
For exposures less than 30 seconds you can use the cable that came with the camera, for longer than 30 seconds, you need something like a Shoestring Astronomy DSUSB and cables DSCBL-01 and 03. See:
http://www.store.shoestringastronomy...roducts_ds.htm
You will also then have to think about guiding and associated problems/hardware etc.
Cheers
JohnG