that URL, for x64, has two conflicting items. There is a para that says: "Windows Server 2003 R2 Datacenter x64 Edition supports up to 2 terabyte (TB) of RAM (with Service Pack 1) on 2- to 64-way. Supported processors include:" (Emphasis mine). Below that in the table it shows a limit of 32 CPUs.

My understanding is that teh W2K3 Datacenter, x64 is limited to 32 CPUs, but I see a whitepaper (http://www.microsoft.com/servers/64bit/whitepapers.mspx) on deployments, that says up to 64 CPUs. I'll ping MS and try to get a more definitive answer.

This one, on Itanium support, (Windows Server 2003 on Itanium), shows 64 CPUs.