For free you can used PHD to do your guiding, and Stark Labs also has a basic program, DSLR Shutter, that will allow you to take a set amount of exposures.
It's very basic software though so don't expect much.
Im not sure what else is around in terms of free, maybe some others can help, otherwise:
http://www.stark-labs.com/index.html
If you have a few dollars to spare then a Nebulosity license is pretty cheap ($80), and it works well for DSLR work.