Apple has just released Mac OS X 10.5.3 update and the changes are not earth shattering.
Most important to me would be this one:
“Addresses reliability issues when performing a full restore from a Time Machine backup.”
[Hint: don't install the Leopard 10.5.3 update for a week or two if you aren't suffering from any of the problems fixed in the list of changes. Why? Remember 10.5.1? That was a fiasco that led to so many problems that 10.5.2 was quickly released to "fix the fixes". Basically, let others find the bugs within 10.5.3 and have Apple fix those before you install the update. If there are any major issues with this latest release, you'll avoid the worst of them by waiting a couple of weeks. I'm actually still using 10.5.0 since it's rock solid and the updates released since don't affect my day-to-day usage. I'd rather have reliability than having all the software that I don't use up-to-date.]
That’d be pretty annoying to use Time Machine religiously and when finally disaster strikes and your backups aren’t fully useable? Ouch.
Regardless, I’d still recommend SuperDuper! for bootable Leopard backups in concert to Time Machine file backups, since Time Machine’s backups do not give you a bootable backup disk to restore from. If Time Machine backups are all you have, you’d have to reload Leopard from DVD, then restore your settings and documents from Time Machine.
With SuperDuper! you could simply connect the drive you used via FireWire/USB, reboot your Mac, hold down the alt key, select your SuperDuper backup and be working from that drive like nothing has changed.
Even more hard-core, you could simply remove the failed drive within your Mac, install the SuperDuper disk in its place, boot, and theoretically you should be operating normally as if nothing had happened.