Microsoft plans to release a new Windows server OS aimed at midsized businesses as well as the next version of its small-business server software worldwide on Nov. 12, the company said Monday.

Both Windows Essential Business Server 2008 (EBS 2008) and Windows Small Business Server 2008 (SBS 2008) will be available that day, the company revealed at its Worldwide Partner Conference in Houston Monday. Hardware providers Dell and Wortmann AG in Europe will be among the first companies to offer hardware for both OSes when they are available, the company also said.

Microsoft expects to post new release candidates for both products on its website next week. Customers also can get information about the products on the site.

SBS 2008, code-named "Cougar," and EBS 2008, 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. Microsoft's goal with these products is 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.

SBS 2008 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.

EBS includes three copies of Windows Server 2008 running on three hardware servers. The first server is a domain controller and management server that includes Microsoft's system-management software. The second server in the EBS stack is for e-mail; it runs Exchange Server 2007 Standard Edition. The third server is a security server running Forefront Security for Exchange Server and Forefront Threat Management Gateway. A premium edition of EBS will include a fourth version of Windows Server 2008 on a fourth piece of hardware running SQL Server 2008.

Microsoft set pricing for both products in May, revealing that the price for SBS 2008 would be going up from the previous version. At the time the company said the price increase was because it had added more technology and services to the offering.

In May Microsoft also said SBS 2008 would only be released for 64-bit servers, although earlier versions of SBS were available for 32-bit hardware as well. The move to 64-bit was not a big surprise, however, as the company has said it plans to offer most of its business software in 64-bit versions only to encourage customers to move Windows Server off of 32-bit hardware.