Oh and another thing about PSP's battery life... I can't remember if it comes with extra batteries, or if you have to buy them... But either way, get an extra set of batteries and (although you'd have to stop in the middle) switch off...
Plus I heard PSP's battery's charge fairly quick... at least when compared to the DS... So if you really wanna go on a gaming binge somewhere where you have access to an outlet, use up batteries, replace and charge, repeat
Or just use the dern AC adapter if you have access to an outlet..