I am not sure if this has been discussed elsewhere, but I have yet to get an iPod (I feel like I'm one of the few left in the free-world without one!) and am torn between the mini, the 3G and the 4G. I know the 'external' usability issues and differences between all three, but does the 4G have any internal / engineering differences that make it worth the purchase? I do remember reading somewhere that the 4G has been re-engineered for battery issues (a.k.a. -- longer life) -- is that true? Are the hard drive and the board / parts more secure - "sturdier" as the generations have past? Are there any additional under-the-hood changes (beyond software / bios updates) that make the 4G more attractive. I'm wondering if saving a few bucks on an older 3G or mini is worth the hassle. Thanks.