Failure Rate Modern HDD's?

I'm just wondering what the likely hood of a HDD failing now a days is.

I am thinking of buying a NAS device and sticking 2 1TB Caviar Black's in and running them in raid 0, then storing all my Movies, TV episodes pictures etc etc. I realize mathematically the failure rate is now twice what it would be if they were just running solo, but what is the likely hood of them actually failing?

I've never experienced a HDD failure (knock on wood) so I'm wondering if I'm just being paranoid about hard disks failing... I guess if they did fail I can just take a day or two and rip all my media again and store it on the array again (after I replace the failed hard disk of course)