If you only need to image a limited number of drives, Clonezilla Live (
http://clonezilla.org) might be suitable. It's a bootable Linux CD (or USB key) which offers basically the same functionality as Norton Ghost. There's a Server Edition as well, for large scale system deployment.
Clonezilla is free, it's very reliable and it's easy to use, even for someone with minimal Linux experience (like yours truly).
The only drawback I've seen so far is the inability to image NTFS partitions with minor file system issues (some cross-linked files, for example); the program reports the error and then exits. Maybe there's a way to override this behaviour, but I haven't found it yet. Otherwise Clonezilla works just fine.