Microsoft has uploaded the second release candidate of Service Pack 1 (SP1) for Windows Server 2003 amid a hail of security patches.

The 445MB second release candidate should improve robustness, but does not offer significantly different functionality except to help security configuration and to update wizard assistance.

"Windows 2000 was a security free-for-all but Windows Server 2003 is getting much more secure," said Barry Feist, a technical consultant at systems integration firm Conchango.

The final version of SP1 is due in the first half of this year, together with 64bit versions of Windows XP and Windows Server 2003. Service Pack 1 is primarily designed to improve security but also offers 64bit processing support.

Microsoft also issued 12 security warnings last week, including eight "critical fixes", as part of its ongoing policy to release updates on a monthly basis. In addition, the software giant issued its Enterprise Scanning Tool program to help companies deploy the updates. This new tool acts as a supplement to the Microsoft Baseline Security Analyzer, helping to detect vulnerable computers, said the firm.

Microsoft also revealed that it is on target to release a first beta of the next version of Windows, codenamed Longhorn, in the first half of this year. The release will lack many originally planned features such as the WinFS file system, the Avalon presentation engine and Indigo web services architecture.

Microsoft is expected to disclose more details at its Windows Hardware Engineering (WinHEC) conference in Seattle from 24 April.