Genealogy software is the best way to organize your research. Here are some options:
  

Family Tree Maker. This is what my wife and I use. Honestly, we did not evaluate all the options. Nevertheless, we have found Family Tree Maker easy to use. The 2008 version has several useful upgrades. Click here for more information on Family Tree Maker at Ancestry.com.

Personal Ancestral File. This is available as a free download. It does not have the full range of capabilities of Family Tree Maker. Click here for more information on the Personal Ancestral File.

Geni. This is a free online tool for understanding and staying in touch with your family. Geni lets you create a family tree through a simple interface. You can expand your tree by adding relatives' email addresses. They will be invited to join your tree and can add other relatives. Your tree will continue to grow as relatives invite other relatives. Click here for more information on Geni.

Also see

Genealogy on the Internet