While many Windows watchers have been keeping a close eye on the forthcoming Service Pack 2 for Windows XP, Microsoft is working simultaneously on another service pack: the first for Windows Server 2003.

Microsoft has said to expect the final Windows Server 2003 Service Pack 1 (SP1) release to ship in the latter half of 2004. It has not said when SP1 will enter broadscale public beta testing.

But earlier this week, according to the ieXbeta Windows enthusiast site, Microsoft released to a group of private testers a third interim test build of SP1.

Like XP Service Pack 2 (SP2), Server 2003 SP1 will include a number of new security features. The private testers are working with the client inspection, remote procedure call (RPC), Distributed Component Object Model (DCOM) and firewall enhancements.

SP1 also is slated to lay the groundwork for Windows Server 2003's 64-bit support. The latest test build, No. 1184, adds support for 64-bit Extended Systems — i.e., systems running AMD Opteron and Athlon 64-bit processors — according to information from the ieXbeta site.

Microsoft has said it plans to roll out a number of new Windows Server 2003 64-bit SKUs simultaneously with SP1. Beta testers are currently testing these SKUs.

"The Device Driver Kit [DDK], Platform Software Development Kit [PSDK] and Customer Support Diagnostics [symbols] included in this release also include support for 64-bit extended systems," according to the note Microsoft sent testers, ieXbeta said.

Build No. 1184 includes not just new features, but quite a few fixes, as well. One such fix is the addition of new support for WOW64, the 64-bit emulation layer that is part of Windows Server, enabling it to run the 32-bit .Net Framework.

Other SP1 fixes are designed to increase the availability and performance of Windows Server 2003, testers said.

With SP1, Windows Server 2003 can achieve as much as 99.9997 percent availability (compared with 99.998 percent without the service pack). Microsoft also is touting a 10 percent improvement in X86 64-bit support with Service Pack 1 (based on NetBench statistics), testers said.

NetBench is a licensed PC Magazine benchmark program that measures the performance of file servers as they handle network file requests from clients. VeriTest, a division of Lionbridge Technologies, developed NetBench.