A version of Windows for servers significantly updated from Windows Server 2008. Questions about administering Windows Server systems that are specific to a business environment are off topic for Super User; please consider asking on Server Fault instead if your question is on topic there.
Windows Server 2008 R2 is a significantly updated version of Windows Server 2008. Unlike Server 2008, 2008 R2 is only available in 64-bit versions. No 32-bit version exists.