I'm suspicious of anything that's free. It's really, really rare to find quality freeware. Writing good software is hard work, and even people who enjoy it usually don't do it for free for very long.
Anyway, TrueImage isn't free, but it's very good value for the money. I've saved and restored entire machines with it on many occasions, and it works very well. These days I just take complete TrueImage backups of my machines, and if a disk fails, I replace it, restore it with TrueImage, and I'm back in business in 20 minutes. For machines that are used by many people, it's also a good way to fight malware—instead of running some intrusive, bloated antivirus package, I just wipe the machine clean with a restore of a virus-free system from time to time (obviously, this is practical only for machines that aren't going to be holding any new files, since the restore puts everything back they way it was before).
I haven't tried Ghost, but since it comes from bloatware specialist Norton, I'm not keen on trying it.