I haven't come across much in the way of good hard disk imaging software that is freeware (you could try a google search) and probably less when you talk of Vista compatibility.
Personally when I'm talking about a critical piece of software like disk imaging and the capability to recover from a catastrophe, I don't want to find that there are any errors or issues when you try to restore a back-up image. When you do get one you should test it by recovering a none essential partition, etc. before using it for the first time when the dark and sticky stuff hits the fan.
It is to a large degree a one of expenditure you don't have to buy it every year and believe me use it just once to save your a** and the cost has been more than recovered.