Here you go: http://support.microsoft.com/kb/317590.
If you configure dynamic updates, the clients will basically update DNS with their information any time the client renews and IP address, performs a ipconfig /registerdns, or the DHCP lease for it's address expires and it gets a new address from DHCP. See the section called "How Windows 2000-Based Computers Update Their DNS Names".
You can also set the DHCP server itself to update the DNS records independent of the clients. This method will likely give you a more accurate record (provided you manually enter all static IP records into DNS). See the section on "Integration of DHCP with DNS"