Microsoft will release the delayed "x64" versions of Windows Server and Windows XP at the end of April.

General availability looks likely to be announced at its annual Windows Hardware Engineering Conference (WinHEC) in Seattle. The products had an original target of the end of 2004.

In Windows Server 2003 x64 Editions and Windows XP Professional x64 Edition, Microsoft will give the option of running both 32-bit and 64-bit applications on the same system. The software is designed to run on computers equipped with processors with 64-bit extensions from AMD and Intel.

Such 64-bit systems offer users greater computing power as they can process more data per clock cycle and can use larger amounts of memory. AMD's Athlon64 and Opteron processors, as well as Intel's Xeon processors, currently support 64-bit extensions.

The availability of the operating systems comes long after the processors shipped. Microsoft has said it will offer a swap program for Windows Server 2003 that will let owners of systems with the AMD and Intel processors trade their current server operating system product for a version that supports the 64-bit systems at no additional cost.

Microsoft released near final test versions, called Release Candidate 2, of Windows Server 2003 x64 Editions and Windows XP Professional x64 Edition early last month. At the same time the company released RC2 of Service Pack 1 for Windows Server 2003. Release Candidate 1 versions of the products were released in December.