The only real reason to get a PSP is for N64 emulators which aren't even 100% yet. You can complain all you want about shovelware and kid crap on the DS, but DS gets some of the best games hands down at the cost of graphics. And any real gamer will say that they'd prefer fun games over pretty games any day.
Not to mention as far as running games, the DS takes over by FAR. With an 8 GB card for $10 on amazon that can house more DS games than the amount of "Good" or better titles in the entire PSP library. Mind you a PSP can use 8GB cards, but its suddenly less impressive when the average PSP game takes atleast 600MB. And the downloading is grueling. If you want to play PSP's blockbuster titles, they're often 1.3GB + are often too large for HTTP download, and you have to rely on slow torrent downloading that could take as much as hours to days. Compare that to a 3-5 minute download of a 128MB game.
Even with the shovelware, the DS boasts 4000+ Roms and isn't slowing down and is popping out at least 25 games in America a month. The PSP on average, 6. And the PSP isn't imune to shovelware and bad games as I'm pretty sure I saw an ad the other day for a Hannah Montana game for PSP.
And as a PSP owner, the only games I have to look forward to is Little Big Planet, Dirt 2, and Kingdom Hearts.
As a DS Owner, I have Golden Sun, a new Zelda, Gauntlet, NFS Nitro, an F-Zero clone (if it gets published), Dirt 2, Scribblenaughts, Countless RPG's, Wario Ware, even more Wifi-games, a hack for New Super Mario Bros that mimics the Lost Levels, the list goes on.