Here are a couple of good blog postings that should assist greatly in implementing Kerberos authentication.
This first article by James gives a good overview into how Service Principle Names (SPN’s) operate and some important gotchas. Click Here.
This next article offers a complete step by step process for installing MOSS, and unlike most other articles actually instructs how to implement Kerberos authentication. Click Here.
Another article that gives valuable information regarding enabling Kerberos for SharePoint. Click Here.