Theres a Imaging program built into Windows itself. Although, I do not like it myself.
The 2 most popular around these forums would likely be Macrium Reflect & Acronis.
There is a Completely Free version of: Macrium Reflect
Theres a tutorial here for this one. Imaging with free Macrium Acronis
is a fully featured backup & restore application, and has more features than the free version of Macrium.
this is my personal favorite. (Has a 30 trial)
However, Macrium Reflect also has a fully featured paid version.
So it ultimatly comes down to preference IMHO.
There is also Paragon Backup and Restore. I know little about this one however.
Depending what HD you have, you may be eligible for a Free, although basic/stripped version of Acronis.
All you need to do is register it and download.