As the owner of a tired, but still beautiful GENIOe, I can attest to the versatility of dual slots. Having them really does extend the life of your device. That said, who cares? HD vs Solid state is a silly argument. It's all about different strokes for different folks. If you don't expect to keep your device for more than two years or so, HD's are good storage option. They're cheaper and should last you two years easy. On the other hand, if you keep your device (like I have) for three years or more because you have three kids and a mortgage, going from 128 to 256 and someday in the future, 1 gig, is invaluable as your removable media becomes your messy file cabinet and the other slot is still open for accessories and temporary cards. If I had the money, and I didn't think my wife would kill me for doing it, I'd get both just for kicks.
