in this link (http://technet.microsoft.com/en-US/evalcenter/dn205292) you can get the info to download the evaluation versions for Windows Server, SQL Server, System Center, etc.

here are the direct links (you need to register to download)

 

Windows Server Evaluations

System Center and Windows Intune Evaluations

SQL Server Evaluations

Windows Azure Evaluation

Windows Azure Pack

 

Enjoy!

Jose