Microsoft on Tuesday revealed pricing details for a new server software bundle aimed at midsize companies and the next version of its Small Business Server product.

Microsoft also made available preview versions of those products -- Windows Essential Business Server 2008 and Windows Small Business Server 2008 -- for download and evaluation.

Both products have been undergoing private testing. Tuesday's previews allow Microsoft to receive feedback from a larger audience before releasing the products, which it expects to do by the end of the year, the company said.

Microsoft is offering a standard version of Windows Essential Business Server 2008, including five CALs (client access licenses), for $5,472; additional CALs will cost $81 each. CALs are required for each desktop user accessing server software products from Microsoft. A premium edition of Essential Business Server 2008 will be available for $7,163, a price that also includes five CALs. Additional CALs for the premium edition will cost $195 each.

Windows Small Business Server 2008 Standard Edition, with five CALs, will cost $1,089, Microsoft said. Additional CALs for the software are available for $77 each. A premium edition of the product, including five CALs, will cost $1,899; additional CALs are $189 each for that product.

Pricing for Small Business Server has gone up from the current version of Small Business Server 2003 R2, which is $599 with five client access licenses for the standard edition and $1,299 with five CALs for the premium edition. Microsoft said the pricing has gone up because the latest version of the product includes more technology and services than the previous version of the product.

Microsoft Windows Small Business Server 2008, formally code-named "Cougar," and Windows Essential Business Server 2008, formerly code-named "Centro," are part of Microsoft's new Windows Essential Server Solutions line. The products in the Essential line combine Microsoft's Windows Server OS with other software products the company deems necessary to running a business, to provide what it describes as an all-in-one, easy-to-install software stack for companies that may only have a small IT support staff.

Essential Business Server includes three copies of Windows Server 2008 running on three hardware servers. The first server is a domain controller and management server that includes the Windows Essential Business Unified Management Console.

System-management products in the offering include Microsoft System Center Essentials, Active Directory Domain Services, DHCP and DNS, all of which are built onto Windows Server 2008. The second server in the Essential Business Server stack is for e-mail; it runs Exchange Server 2007 Standard Edition, Microsoft said. The third server is a security server running Forefront Security for Exchange Server and Forefront Threat Management Gateway.

The premium edition of Essential Business Server 2008 will include a fourth version of Windows Server 2008 on a fourth piece of hardware running SQL Server 2008, Microsoft said.

Aside from its price and new features, another change to Small Business Server 2008 is that it will be offered for 64-bit servers only; previous versions were available for 32-bit servers. Microsoft has said that going forward, it will be offering most of its software in 64-bit versions only, to encourage customers to move to the 64-bit version of Windows Server. For instance, the latest version of Exchange Server is available only for x64 servers, while previous versions also supported 32-bit hardware.

Small Business Server is an integrated offering of Windows Server 2008, Exchange Server 2007 Standard Edition and Windows SharePoint Services 3.0. It also includes Microsoft's Office Live Small Business service and 120-day trial subscriptions to Forefront Security for Exchange and Windows Live OneCare for Server. The premium edition of the software includes an additional license for Windows Server 2008 and SQL Server 2008.