From experience i can say that if you want a rugged device that will stand up to a lot of damage, you are going to be best most likely to go with a zune 30. I know people who have done horrible things to this device and had it survive. I myself accidentally smashed mine a few times. The newer zunes, and the iPods for sure are not going to stand up to much damage.
I've never owned a hard-drive based player but I'm considering one so I can put my entire music collection on it- about 30 gigs plus I want room for expansion. I'm considering the Zune and the iPod Classic but I'm concerned if they skip or are easily damaged. I ride my bike off road and the player WILL eventually hit the ground. How fragile are these hard-drive players?