Hi Mark,
business reasons for moving to FQDN; main one being future expansion of the network and being able to stay current with desktop OS and server OS software. As well Exchange has been kind to let us go to SP1 with a single label but I doubt they'll continue that practice.
as well I found the following:
Problems that are associated with single-label namespaces include the following:
• Single-label DNS names cannot be registered by using an Internet registrar.
• Domains that have single-label DNS names require additional configuration.
• The DNS Server service may not be used to locate domain controllers in domains that have single-label DNS names.
• By default, Windows Server 2003-based domain members, Windows XP-based domain members, and Windows 2000-based domain members do not perform dynamic updates to single-label DNS zones.