PS3: your HD is linked to ONE PS3 so remember to make full back-ups!

Truth be told I never thought about doing PS3 back-ups for a couple of reasons:
1st: I think the PS3 is a brilliant and solid piece of hardware
2nd and most important: I've got my 250GB hard disk installed so in case I'll just mount it on a new machine...

I discovered just too late that no other PS3 will read my hard disk unless I format it (that means all my data will be erased).
As for some data the PS3 hard disk is linked to only 1 PS3 and will not work on any other PS3.

So, basically, if your PS3 breaks for any reason even though you have all your precious saves and data on your hard disk it will be useless because you cannot read/transfer them on any other machine.
At least... that's what I've experienced.

What I'm basically suggesting is: do your bi-weekly or monthly full back-ups (using the PS3 back up utility) to make sure you won't loose your stuff!
The full back-up will take quite a while (1 - 2 hours so plan it for when you won't be using your PS3 for gaming :)).
Check here for instructions: http://manuals.playstation.net/document/en/ps3/current/settings/backuputility.html

You will not lose trophies information in any case since they are linked to your account outside your PS3 (but remember to syncro them every once in a while, if you care).

Happy gaming!
Ivy