Family Tree DNA (www.familytreedna.com/) is the company which does DNA tests for the Holden surname group. From their home page, you can click on surname projects (www.familytreedna.com/surname.asp) to see other surnames you may be interested in and frequently asked questions (www.familytreedna.com/faq.html) for other general information.
DNA 101 (http://blairgenealogy.com/dna/dna101.html) is a general description about how DNA testing works.
Contexo (www.contexo.info) also has basic information about DNA.
Chris Pomery’s DNA Portal (http://freepages.genealogy.rootsweb.com/~allpoms/genetics.html) contains a good description about how DNA tests can benefit the family historian. While on this site, click on "List of Y-Chromosome DNA Studies" to see a list of family surname studies already underway. Also go to paragraph 1.2 on the Pomery web site, "Representing the Results of DNA Studies", and click on the links for Mumma, Stiddem, and Dooley to see some examples of how other families have displayed the results of DNA surname studies.
The Lentz/Lance Molecular (DNA) Genealogy Project (http://freepages.genealogy.rootsweb.com/~gbonner/lentzdna/) shows how a specific question that could not be answered by traditional genealogy research was answered unambiguously by DNA technology. It looked at descendants of four Lentz men, who were thought to have been "brothers" living in Rowan County, NC in the late 18th century. Results showed that only two of them were brothers, and the other two were not. This page also contains a good description about X and Y-chromosomes and how the Y-chromosome can be used for family surname studies.
A list of links with general information about using DNA for genealogy research can be found on:
Revised May 8, 2004