For psp you'll need custom firmware, one that'll run 1.5 homebrew - run over to pimpstreamer and get going. You'll have to muck about with the conversion rates if your wifi is a little bit slacky.
For iphone I'll recommend Air Video. Works a treat and you won't have to convert all your nice avi files. It'll convert on the fly - on a dual core machine or higher. Runs fine with my little HP 3020 Slimline PC and that's something like a AMD x2 3800+ if memory serves me right.