Here is the sharepoint 2007 form authentication for sqlserver membership.
I have read this article and it is good for form authentication.
http://weblog.vb-tech.com/nick/archive/2006/06/14/1617.aspx
http://www.andrewconnell.com/blog/articles/HowToConfigPublishingSiteWithDualAuthProvidersAndAnonAccess.aspx
http://weblog.vb-tech.com/nick/
http://www.chandima.net/Blog/archive/2007/02/15/how-to-setup-and-configure-forms-based-user-administration-feature-release-1-0-beta.aspx
http://www.codeproject.com/KB/sharepoint/FBA.aspx