ka for the psp u can i think yull liek this watch movies that u loaded onto a memory stick listen to music of course and with the slim (i suggest it) viedo out put skype also add on camera also u can download games if u hack u psp(i trust that you will only donwload open source games lmao)
remote play with yor playstation over wirless and internet also u can use as sort of playstation 3 controller with suported games
u can also buys games threw playstation store(i love this feture) i get around 4 hourse battery life it can out put 480p (u can use a tv as a screen)
i wasd in your position but finaly got one with a 4 gig memmory stick and i love it!!! especialy for movies free converter here :
http://www.pspvideo9.com/
it is worth it