hmmm well the psp's games are better but the ds's layout is definitly better than the psp but the grpahics on the psp are much better but i think the ds is slightly faster even tho it doesnt look it but i am going with the psp as i am a big sony fan.
PSP .. PSP has more functions and better games.. i like the mario games, etc. as well .. but tekken, loco roco and gta are pwnage
obviously the psp, internet access,mp3,games etc i had the original DS didnt like it. but im not sure about the Ds Lite
PSP is the best the DS might have better games but the PSP has all the other things that makes a good handheld and the good games are coming up so all we have to do is wait, and while we wait you can hear music or watch a movie on your PSP
Each system has its own pros and cons. Instead of just asking here to listen to people argue, I highly suggest trying them out and buying whichever you prefer. I'm sure you have some friends that own one, or maybe just use the demos at video game stores. Good luck.