hmmm...free? Thats a tall order... You could give Elbrus a go. Never used it, but have heard reasonable feedback -
http://www.astrosurf.com/pulgar/elbrus/elbrusin.htm
More commercial options are;
CCDSoft coupled with TheSky
MaximDL coupled with Pinpoint
If you specifically detail what you're trying to achieve, then it will be possible to point you in the right direction (pun intended).
Cheers