I would recommend using the DRBL livecd. It contains the clonezilla program, as well as a few other useful utilities, and it boots into a gui. It's intended purpose is to facilitate imaging multiple computers over a network at the same time, but it works great for single computers as well.
Here is the link to the clonezilla livced guide.
Also, keep in mind you can only image to a partition of equal or greater size. It doesn't matter if 90% of the image is of free space, it wont work. Atleast not last time I checked.