As expected, Microsoft posted a revamped virus and worm cleaning utility Tuesday, the first of what it's said will be regular monthly updates to the tool.

Dubbed the Microsoft Malicious Software Removal Tool, it cleanses PCs of eight different worm/virus families, including Berbew, Doomjuice, Gaobot, 2003's destructive MSBlast, MyDoom, Nachi, 2004's Sasser, and Zindos.

Windows XP users who have Automatic Updates enabled automatically retrieve the tool each month, while those using Windows Update also get the utility as part of any update package. Windows 2000 and Windows Server 2003 users must manually download the tool from the Microsoft Web site or use the online version.

The tool doesn't remain resident on the system -- it runs, then essentially uninstalls itself -- so it's no substitute for anti-virus software, Microsoft said in documentation accompanying the utility.

Only threats that Microsoft rates as "Moderate" or "Critical" will make it into consideration for inclusion in the utility as the months unfold.

"This is not Microsoft's foray into the anti-virus market," said Jupiter Research analyst Joe Wilcox in a statement on his blog. "That's not to say Microsoft isn't planning to release software with anti-virus capabilities [but that] today's release isn't it."

More information about the removal tool can be found in this document on Microsoft's support site.