Go with the PSP if you are looking for entertainment value. If you need a cell phone why not get a cheaper phone or get one of those free or reduced priced phones when you sign up for a two year agreement.
i'm stuck. I'm can't think what to get a PSP or a Samsung D600 Cell Phone. either way i'll spend about the same amount of money. i know that they are completely items but i just have enough money for one or the other.