Sorry, but I'm going to have to disagree.
Aside from actual physical harddrive damage, magnetic drives will simply die sooner or later simply due to the way they save information. (Magnets lose their strength after a certain while).
Harddrives in laptops seem more prone to physical damage in my experience (we had 2 dead 2,5" harddrives in my family in 2 years), simply because they're also subjected to more movement and jolting.
Since this one is is used in a desktop machine, it should last as long as a 'regular' 3,5" drive.
But assume it could fail at any given moment and backup your data regularly, regardless of whether it's a laptop or desktop!
I'd say most harddrives have a life span of between 3-5 years.