The LAST one I'd touch is PSP. Proprietary movie format for UMD, where they charge you twice what a DVD version would cost you. In addition to that you can't use the full resolution of the screen (480x272, substantially lower than even *Standard definition* TV, for chrissakes!) when ripping movies in MP4 format to play back. It doesn't play back DivX, Xvid, etc., and as far as I'm aware there are NO codec downloads available. Memory sticks are *absurdly* overpriced and have very little space available. There's a 3rd party hard drive addon, but it turns the PSP into an ugly, bulky monstrosity.
If she's interested in movies primarily, get her a portable DVD player or one of those portable media centers. Either one will meet her needs MUCH better than a PSP. PSP is basically a portable PS2 with half-assed movie and MP3 playback integrated. Even at games it's got all of *two* decent titles out (Lumines and GTA:LCS).
PSP is overpriced and undercapable, period.