Run 2 Servers identically

Hi All:

I currently have 2 servers at my office, one of them is my primary server and I'm currently not using the second one. I want to do a Full Disk Imaging or Mirroring of my primary server and transfer it to my second server 3 times a day automatically. I want to have a full copy of my primary server on my second server in case my primary server fails. If my primary server fails then I can use my second server as my primary and my network will continue to work normally.

How is the best way to accomplish this?