I've heard good things about Clonezilla. [URL] but have never used it myself.   The only drive imaging software I've ever used is Acronis True Image. (not free) It's never let me down.   Just out of curiosity since you'll need a new drive to clone to, why not just remove the current drive with Vista and install the new one for your Ubuntu install? That way you know for sure you have an intact Vista drive with a working recovery partition and won't need to worry about cloning software.
Hi! I have a dell studio 540 with vista pre-installed. I have an OS partition(C:) and a recovery partition(D:). What I want to do is to make a 1:1 clone of the harddrive to an external drive. The reason for this is that I want to dedicate the entire hdd to ubuntu linux(deleting the recovery partition and windows partition), and if I change my mind later on I want to be able to restore my system from the image in a fully functional state with a working dell factory image. Is there any requirements for the recovery partition to work properly?  Will it refuse to restore the hdd if the partitions are altered?  Any tips on a free program that can make a complete copy of a hdd (sector-by-sector copy) and ensure a working computer after restore?   Thanks!          
Backup entire hard drive for future use - switching from windows to ubuntu