Uh huh; if you're backed up, all you have to do is run to the store, grab an internal hard drive for 60 bucks, run back, pop in the installer CDs, and you'll be back up and running within 3 hours of when the computer died.
But if it's very quiet, faint ticking then it isn't anything to worry about. if it's constant ticking with a rhythm like tick tick tick tick then you "might" have a dying drive.
But if it's one or 20 very fast, quiet ticks once every day or something random, then you're good.
If this drive eventually fails, I plan on getting a SSD, I don't have a lot of files, so I can get by with one.
I know the tick is in the HDD bay, it is also audible over the TV, It has probably happened 15-25 times in the past 2 days.