Domain Controller Logs for authenticaiton requests

We are planning upgrading our 2003 functional Level Domain to 2008 with a transitionayr approach involving new Domain Controllers (built W2K8 x64 Enterprise).  We will be swapping the IPs of the current Domain Controllers with the new DCs but we are going to be using new names for the new DCs.  Are there any tools or methods to peruse the logs on the old DCs to get a list of applications and/or machines that are still authenticating against the to be decomissioned old Domain controllers?

We're trying to generate a list of things like ESX AD-Auth (points to specific DC names), Citrix AD-Auth, SPAM appliances and other applications that may have hard coded entries for our old DCs and we're wondering what tools or methods have been used to harvest a list of devices going against a to be decommissioned Domain Controller (this is a large enterprise environment).