Operating system not supported for installing Parallels Site Builder?

[BrasilS]

Hello, I'm trying to install the parallels site builder 4.5, my OS is Windows Server 2008 R2 Standard.

When trying
to install I get the message:

"This product is not supported by your operating system. Please use either
MS Windows 2000, MS Windows 2003 or MS Windows 2008 server."

What is the correct version of Windows 2008 I use?

Thanks.