Microsoft's SMS, or Systems Management Server, is a big deal in corporations around the world. The newest iteration isn't called SMS 4, but rather, System Center Configuration Manager 2007, or SCCM 2007 for short. However, because I'm an old-school kind of guy, I'll just call it SMS in this brief discussion.
SMS costs an arm and a leg, has a thoroughly esoteric licensing scheme, and requires a client component on every Windows PC and server on your network. But, if you can get over these drawbacks, it houses a pretty amazing collection of core features:
Software and Hardware Inventory
Operating System Deployment