A standing complaint about Windows Server is its resource footprint. Those in IT just take as rote that it requires lots of memory, lots of CPU, and lots of disk to put any substantial services on the air with Windows Server 2003. I think it's safe to say that the typical x86 rack server's characteristics reflect the requirements of Windows Server. Microsoft's big OS has always been designed under the presumption that it will have a full physical server to itself.

The Bottom Line Microsoft Windows Server 2008 Microsoft, microsoft.com/server Very Good  8.5 criteria score weight Management 7 20% Performance 9 20% Scalability 10 20% Features 8 15% Security 9 15% Value 7 10% Cost: Standard: $999 with 5 CALs, $1,199 with 10 CALs. Enterprise: $3,999 with 25 CALs. Datacenter Edition: $2,999. Windows Web Server 2008: $469. Platforms: 32-bit or 64-bit AMD or Intel x86, or Intel Itanium CPU, with minimum speed of 1.4GHz. Memory and disk requirements vary by edition and features. Author’s recommended minimums for Windows Server 2008 Standard are 1GB of server RAM per virtual instance and 40GB of local hard disk for boot and swap. The GUI-less Server Core’s requirements are much lower. Bottom Line: You couldn’t ask for more, or for less. Windows Server 2008’s fine-grained, modular configurability lets you shrink the OS footprint down to virtualization guest-friendly size, and Server Core drops the Windows GUI to dramatically reduce the memory requirements of a virtualized guest. This server OS presents a minimal attack surface for guest and host instances, and generally removes the requirement for add-in server and client security. It isn’t a server in a box, but it’s Microsoft’s richest server OS by far. About our Reviews and Scoring Methodology

In Windows Server 2008, Microsoft delivers a 64-bit server OS with a smaller minimum resource footprint than Windows Vista. It varies by edition; Windows Server 2008 Datacenter doesn't focus so much on shedding the pounds, but it, too, picks up the speed benefits from the slimmer Server Core, which was created to be a practically weightless virtualized guest OS. IT shops are likely to use Windows Server 2008 the same way they use Windows Server 2003 now, only now they can run lots of independent virtual Windows Servers that scale in features and footprint across a broad range of options.

[ Read InfoWorld's tips on making the most of Windows Server 2008's easy-to-miss new options ]

Windows Server 2008 remains a component of the Windows Server System, so Microsoft has not instituted a free lunch program. Functions like e-mail and collaboration, database, and robust edge services are add-ons that most deployments will require. But these can be placed at the host level, with virtualized guests distributing applications and services that utilize Windows Server components. In other words, one license of Exchange Server or SQL Server will stretch further than ever before.

How low it can go
I spent most of my time testing Windows Server 2008 Enterprise on an eight-core, two-socket AMD Barcelona reference server. When you align the features of the Barcelona architecture with Windows Server 2008's capabilities, you come away with the impression that AMD designed its CPU with Windows Server 2008 in mind. Having talked with Barcelona's architects, I'll bend nondisclosure just enough to say that to call Barcelona a Windows Server 2008 hardware architecture is not far-fetched.

Windows Server 2008 is built for virtualization. All SKUs up to Datacenter are tooled for what you might call "buffet" scalability. You can choose, with finer granularity than is possible under Windows Server 2003, the server features you want to run, where you want to run them, and what portion of total resources are dedicated to them. For example, Internet Information Services (IIS) 7.0 has split Web application services functionality into some 40 independently loadable plug-ins. It is similar in concept to Apache's modular approach, but IIS's approach is safer, more transparent, and much easier to manage. This is a nice fit for server roles, a feature introduced in Windows Server 2003 that provides simple on/off switches and wizards that bring up and shut down groups of services according to need. Windows Server 2008 continues Windows Server's tradition of server roles, but adds finer-grained, modular control over individual features. You can still do a blunderbuss deployment in which a Windows Server host or guest role is "all," but it is well worth IT managers' and administrators' time to learn to match server roles, and modular services within those roles, to user and application requirements. Do that, and you'll have servers that will make physical-to-virtual transitions and virtual machine relocation uncommonly easy.

One road you won't need to take to slenderize Windows Server 2008 is to run it as a 32-bit (x86) OS instead of 64-bit (x64). You've heard hype that the overhead of going to 64 bit, especially for virtual guests, is substantial enough to blow x64 off unless you know you need access to a 64-bit virtual address space (as if that knowledge were easy to come by). Dismiss this as noise. The 32-bit server OS is the HD DVD of IT, even for virtual guests. It's time to step into the future.