Backing up with Disk Utility

This is lengthy but I hope I'm presenting some info that may be new to some. I want to back up my Emac (40gB) to my external drive. I've heard of SuperDuper, but it's not clear to me if you have to register and pay for its important features. I have Retrospect Express and I use it because I already have it, but I've read bad things about it at these two links:

http://blog.plasticsfuture.org/2006/03/05/the-state-of-backup-and-cloning-tools-under-mac-os-x/
http://blog.plasticsfuture.org/2006/04/23/mac-backup-software-harmful/

I've made a backup using Apple's Disk Utility, which they say works well. I use the "restore" feature to do it. The backup is bootable, I tried it and it seems to work. There might have been one glitch about what app was supposed to open one file, but I'm not sure. The only thing is, I have to leave the stuff where it was put, in the main directory of the drive. If I put the backup stuff in its own folder, it won't recognize it and boot off it. So, I put all the non-backup stuff in one folder instead.

I'd like to protect my stuff, so I was thinking of putting it all in an encrypted disk image. If I do that, I'll probably do the "restore" thing again, but I'll delete all the non-essential things. That way, I'll have a disk I can boot off of, but I have to open the disk image to get at my stuff and restore it.

So anyway, I was wondering if this is a good backup tool and if it's a good idea to put the backup into a disk image. Do I have to use the "restore" feature, or can I just make a new (preferably compressed) disk image of the internal drive? (Not using the "restore" function to make it) It seems that I can restore from an image.

I've been really conservative about downloading new software and stuff. I want to make sure I have a good solid backup and then I want to change a lot of stuff and do more.

Also I'd like to know if I could boot my backup on a different computer, say an Intel Mac.