I’ve been using this robust and FREE program for several years and rather than repeating what’s so good about it (and outlining its limitations) I recommend reading this: http://www.gensoftreviews.com/?p=126
It, and the companion program that allows you to produce a huge variety of charts and reports, can be downloaded from : http://www.familysearch.org/Eng/Home/Welcome/welcome.asp .
The add-on can be upgraded (when I got mine it simply meant sending a £5 cheque to Birmingham, England and then swiftly receiving two CDs in the post) and is certainly worth every penny.
There are several other programs on the market (no, I haven’t tried them!) but PAF is definitely worth downloading.