I backup once a week (usually when I'm doing some housework and thus can't use the computer) using CarbonCopyCloner. I probably test that backup about once a month.

There's just something about TimeMachine that sits uneasily with me and I figure if I delete something, it's meant to be deleted.

I backup religiously every weekend and store the backup off site at my office (in my cupboard - lol).
I have an alternating backup strategy where one backup is always on site and one is off site - however, until this post I had never actually tested a backup.

Sssoooo, I tested my backup today - booted into my firewire backup I did this afternoon perfectly, no problems, nada, very impressed with Super Duper as a backup solution. I have never experienced such ease in booting into a backed up o/s. Being from a windows background I just expected trouble and was pleasantly surprised.

As such I am satisfied that I can restore my complete system with minimal loss in the event of a primary hard drive failure, burglary, fire, etc.

Um, I'm one of those that doesn't "backup" :P

Most important things are my music, photos & documents, so I'll usually burn these to disk before I send it away for something (eg, my recent service)

Macdave you certainly walk the talk. Your backup strategy is inspirational!
I don't have a regular backup plan but I do copy important files and documents to a couple of external drives and have all the import ones on both my imac and ibook.

Time Machine is great. works a breeze and is easy to test. Just browse your folders.

With the low cost of disk space, its really something you can afford to do properly.

I backup my notebook to an external drive which is with me all the time.

From there I backup both my external and my notebook to 2 sets of drives at home running in RAID. One set is time machine (which occurs automatically so I don't think about it) and the other is a manual backup I run of everything although that doesn't happen as often.

Massive duplication but I carry a lot of company data on my notebooks that would be irreplaceable if anything happened, so its not something I can take a chance with.

Doing Photographic work on location, and I can end up anywhere, I travel with a 12 inch Powerbook and 2 external drives which I backup my files so to have 2 copies of all RAW files. Jobs a long distance from home base I do 3 copies of these files and check before leaving each site, as sometimes it is a long way back to re-shoot.

After the work is delivered I then copy all files to 2 different hard drives. I almost lost a lot of work due to a computer crash and no backup, silly me, but not any more, just paranoid

EDIT: and check both copies, just to be sure

I'd have to jump on the same bandwagon, considering my hardware spec, amount of data, external media and so on, if I chose to backup regularly I would have no time to use the machine. I do hardware inspections of the machine including drive mechanical integrity, electrical testing and so forth, which has proven sufficient. In my 10 years of computing I have not lost data, even on the oldest of hardware.