miyuru: Based on the info you've given me, I will suggest that you DO NOT get a PSP. For one, if music's your main concern, get one of the slew of mp3 players out there. True, the PSP gives good sound quality, but for example an iPod's functionality is better. Plus I really disagree about it being the epitome of mp3 playback as Marconelly puts it, because it sounds virtually the same as everything else in my house that plays music - but maybe my ears aren't as sensitive. Seeing as you do have a PS2, and all that jazz, then you might as well just stick to your SP for the occasional need of a game. Despite the PSP's great graphics, the SP simply is in a whole 'nother league when it comes to good games (hell, I think the DS has some better games at the moment).
(FYI I do own a PSP myself, but I just haven't glammored and orgasmed from it like many other folks here on GAF. Ah well.)