Funny, i thought i posted here before... well, I bought a PSP a long time ago, i dont know how the DS is, so i wont talk abouth it.
Since i have the PSP, i use it everyday, when i go out i listen some music (i cant go with some music on my ear
) with the psp, i only had to buy a 1Gb memory card (and i am start thinking on buying another one with more capacity) And when i have some time i just play a little with one of the games i have, o i just wach some series (Anime, like Death Note).
And now i am waitig to the server on the Ps3 on Spain to have the Download option, from a cheap price you can download a PSX game to your psp (FFVII is the one i want).
In short words, in a psp you can have, music/videos/games/photos (you can also select your own background image) it depends the use you will going to give it, but as a PSP user i would recomend you to buy it.
*edit: oh, i forgot the Internet, with psp you can navigate throught the internet if you can find a Wifi conection.