Amazon has added Microsoft's Windows Server to a program that allows developers to try their programs for a free on a limited version of its EC2 cloud infrastructure. The program had previously been available exclusively to Linux server users.

"This is an easy way for Windows users to start learning about and enjoying the benefits of cloud computing with AWS," Amazon Web Services evangelist Jeff Barr said, in a blog post.

The offer applies specifically to Windows Server 2008 R2. Participants can get up to 750 hours per month on an EC2 micro instance, for up to one year. EC2 micro instances supply limited, but consistent, processing power, and allow users to burst to higher levels occasionally. Amazon suggests that users could employ the platform for creating test environments, building AWS applications, or hosting a Web site.

"We've fine tuned the micro-instances to make them even better at running Microsoft Windows Server," said Barr.

After the free trial, Windows Server users can purchase access to EC2 at regular rates, which start at 3 cents per hour for a micro instance, and run to $2.97 per hour for instances that stretch across clusters of up to eight machines.

It's more than just generosity behind Amazon's offer of free space on EC2 for Windows Server users, analysts say. By making EC2 Windows-friendly, Amazon can entice businesses that might otherwise have chosen to deploy their cloud-based systems on Microsoft’s Azure platform. "It’s a logical step," said Gartner analyst Ray Valdes. "There are companies that are moving to the cloud but are not prepared to go to Linux."

The 750 hours of free space is not a random number either--it exactly matches what Microsoft offers in terms of free time on Azure.

The move may also be a warning shot by Amazon, which is currently the market leader in cloud platforms, that it won’t stand idly by while Microsoft beefs up Azure to make it more competitive with EC2. While Azure is seen as a somewhat limited platform as a service (PaaS) offering, compared to Amazon’s more versatile infrastructure as a service (IaaS) EC2 product, there are signs that Microsoft is looking to move Azure in the direction of IaaS.

It's widely believed, though not confirmed by Redmond, that Microsoft plans to add a persistent virtual machine capability to Azure that will allow it to run Linux, and other software that needs to reside in a persistent state environment. Microsoft is also adding Hadoop tools to Azure for Big Data analysis.

"Eventually these platforms may converge in terms of capabilities, though for now they are still quite far apart. But what you’re going to see is a lot of trial balloons with new services," from both Amazon and Microsoft, said Gartner’s Valdes.

Windows Server users who sign up for a trial on EC2 also get 750 hours of free usage time to run Linux, access to Elastic Load Balancer time and bandwidth, Elastic Block storage, S3 storage, and other services.