Gosh, what an awful experience. It's an experience I've had (long ago) that made be very careful.
Others have made some excellent suggestions for backup, so I'll just add a description of my technique.
I have a multi tier backup protocol that I cycle whenever I've done enough work that I don't want to lose it. I have a directory under my VM directory in OSX called backups. I also have several external drives. I keep a backup of my .hdd files in the backups directory, and a copy, using the Finder's file copy command which produces a file called "copy of x" where x is the original.
When it's time to back up, I move the "copy of" files from the VM directory to the backups directory, replacing the old ones. This is quick. Then I use the Finder to make copies of the .hdd files in the VM directory. This gives me two backups on the Mac hard drive.
Then once in a while (about once a week or when I've done enough on the Mac that I don't want to do it again, or when I'm about to do something I may not be able to undo) I backup the entire Mac to an external. I use a program called SuperDuper for this. It's free if you want to clone your Mac to an external drive, but since it copies all the files, it can take a while. It's a good task to let run while you sleep. If you buy the product, it unlocks an incremental mode which copies only files that have changed since the last backup (and deletes files that are no longer on the Mac). I use this with two alternating external drives, and I've never lost anything despite making regular mistakes, some of them really unthinking and stupid, but I'm really paranoid about the backups (which I'm sure you will be from now on as well since I got there by the same route you just did). One advantage of the external drive technique is that if you use a firewire external as I do, the copy is bootable, so if you trash the mac internal drive, just boot from the external, and use SuperDuper to put everything back.
After I make copies of my VM files, I sometimes run the Parallels compressor (and here let me emphasize AFTER MAKING COPIES) which keeps the size of the .hdd files more manageable.
I hope this is useful, and wish you luck in your experiments.
Last edited: Jan 24, 2007