Apple hard drives don't break down any more often than any other manufacturers' -- they are after all the same mechanisms from Hitachi, Seagate, Fujitsu and Toshiba.
Most often, its not the hard drive that's broken but the OS on the hard drive that's borked -- Repairing directory structure (Disk Utiltiy, DiskWarrior, TechTool Pro), reinstalling OS and/or reformatting and reinstalling OS fix this most times.
Laptop hard drives just have a much harsher environment to operate in - subject to movement, shocks, changes in temperature, and overheating, so they fail more than desktop drives (this is common across the board of laptop miniturized, light weight, low voltage components)
Oh, and I'm willing to bet that Mac downtime due to OS problems is WAAAY less than Windows OS downtime.