A lot of choice out there but Macrium Reflect is very good: http://www.macrium.com/reflectfree.aspx
It is simple, reliable, FREE version does only full restores…which I personally prefer anyway over incrementals, and has scheduler in FREE.
Every night (while asleep) I do a scheduled full image…W7 64bit ~120GB I5 PC of data on 500GB HDD to USB HDD…takes about 45 minutes.
They have recovery boot CDs in Linux or BartPE so you can re-image current HDD or if new HDD can map to smaller or higher density one.