In another sign of the growing interest in WAMP setups, at least 12 bundles of the required open-source products are now available to be downloaded and installed on Windows servers. For example, the XAMPP installer created by Berlin programmer Kai Seidler is available for Windows as well as for Linux and other operating systems, including Solaris and Mac OS X. Thus far, more than 80 percent of its 3 million downloads have been made by Windows users, Seidler said. Even Web servers -- a longtime sweet spot for the LAMP stack -- are increasingly being run on Windows hardware, according to Mark Brewer, CEO of Covalent Technologies Inc. in Walnut Creek, Calif.

Covalent provides support services to users of The Apache Software Foundation's open-source products. Brewer said almost one-third of the customers his company supports on the Apache Tomcat server are running the software on Windows. "That had been 15 percent to 20 percent historically," Brewer said at last week's O'Reilly Open Source Convention in Portland, Ore.

In addition, nearly one-fifth of Covalent's customers run Apache's flagship Web server on Windows. Brewer said he thinks that figure is equally significant, considering that Microsoft bundles its Internet Information Server software with Windows Server.

But Microsoft's ability to integrate its own back-end products with Windows gives it a big edge over open-source insurgents in general, said Mike Olson, vice president of embedded technologies at Oracle Corp. and former CEO of Sleepycat Software Inc. Sleepycat, which Oracle acquired in February, developed the open-source Berkeley DB embedded database. But, Olson said, "if I've already got Microsoft [technology] installed on my Windows server box, why would I bother to throw it away and install something else?"