Well the DS has a online cart you can buy now. They also have something to let you turn it into a MP3 player. What people fail to realize is Nintendo is doing it to, people are just more blind to it. They ported super mario 64 to the DS, as well as some other ones.
PSP can play music and movies and internet, people dont need or want that so they pay more to get their DS able to. That doesnt make sense. It could just be me though.