Absolutely, I do a full backup usually once a week to an external LaCie disk (software included) and then I store the external disk in my safe. I learned the hard way, after losing about a month's data when my house got hit by lightning 3 years ago.

Great thing about the external disk is that if you are upgrading computers like you did, you just have to plug it into the new PC and you have full access to all your data instantly. You don't even need any special software as its recognized by XP (& I assume vista) immediately.