Microsoft may be able to claim a record number of certified are applications available for its Windows Server 2003 product as of launch day today. But a number of Microsoft's own applications won't be able to support the new server release right away — if ever.

Legacy versions of Microsoft's SQL Server database (versions 6.5 and 7.0) won't run at all. And SQL Server 2000 will run only with a service pack.

See Microsoft's SQL Server Support Page Here

The same is true of other Microsoft applications. Exchange 5.5 and Exchange 2000 aren't able to run on top of Windows Server 2003, according to Microsoft's Windows Server 2003 applications-support page. And the company's Internet Security and Acceleration Server won't run without a service pack, either.

It seems as if changes that Microsoft made to its Internet Information Server code could be what's breaking a number of its legacy applications.

"With approximately 350 code changes in Windows Server 2003 that affected Exchange, Microsoft determined that it would better benefit our customers to focus development efforts on Exchange 2003 to take full advantage of the new improvements in IIS 6.0, rather then on updating either version of Exchange to run on Windows Server 2003 in IIS 5.0 compatibility mode or Exchange 2000 to work with the new architecture in IIS 6.0," according to Microsoft's Web site.

"As a result, Exchange 2000 needs to be physically installed on a server running Windows 2000 with Service Pack (SP) 3 to coexist in a Windows Server 2003 environment. Exchange 2003 is fully supported on both Windows 2000 Server and Windows Server 2003 running IIS 6.0," the explanation continues.

However, some testers reported on their Web sites that they have been having problems getting Microsoft Exchange Server 2003 "Titanium" beta releases to load on the near-final Windows Server 2003 versions.

Read Microsoft's Exchange/Windows Server 2003 Support White Paper

Some beta testers also have been reporting that they have been unable get BizTalk Server 2002 to work on top of the later beta builds of Windows Server 2003.

Microsoft is saying it is working on a Service Pack for BizTalk that will fix this problem but that it won't be available until some time in the next couple of months.

Read Microsoft's BizTalk Server Update Here

Microsoft has been whipping out updates to some of its other applications so they will support the new operating system. For instance, Microsoft last week posted an update to its Project Server 2002 product that can "take advantage of enhancements exposed in Internet Information Server 6.0," embedded in Windows Server 2003.

Just last week, Microsoft rebranded its Windows Server 2003 — plus a number of server applications, including SQL Server, Exchange Server, ISA Server and BizTalk Server — as the "Windows Server System."

Read More on the Windows Server System Brand