Does anyone have experience trading in their used laptop for a new model at retailers? I have a last gen PowerBook G4 12" that starts to run very slowly recently. I will be getting a MacBook Pro to replace it. Does it have any value at all? Should I... a) Trade it in; b) Sell it in the classifieds (craigslist?); or c) donate it somewhere - if so, where? Thanks for any input. Cheers!