The System Center Technical Preview released at the same time the Windows 10 Technical Preview did. Available through the new TechNet Evaluation Center and as a download for MSDN subscribers, Microsoft is intent on showcasing what's next for its management suite designed for the Cloud. The on-premises piece of System Center, Configuration Manager, won't see its own Technical Preview until sometime in early 2015, so the specific products available to test now all have decidedly Cloud ties. What's available for testing now is Orchestrator, Operations Manager, Data Protection Manager, Virtual Machine Manager, and Service Manager.
Downloads and Azure images have been available up to now, but Microsoft has released VHD files for each of the products available in the current Technical Preview. VHDs, of course, are Virtual Hard Disk files, and can be used to easily boot a virtual machine to start testing more quickly, retain custom settings, and allow you to start from a scratch installation if you need to.
The VHDs are available at the following links: