Silent Hill Origins review at PSP Fanboy.

"The franchise of Silent Hill has generally fallen under the responsibility of Konami's Japanese development team, Team Silent. This team was actually split up between Silent Hills 1 and 3, and Silent Hills 2 and 4. If you're knowledgeable about the SH universe, the first and third titles tell an ongoing story about the town, Alessa, and the lineage of Harry Mason. The second and fourth were more abstract concepts, the second game exploring what exactly the town of Silent Hill is and the fourth was just a bit more wild in ideas, loosely connected to Silent Hill by the villain: Walter Sullivan. The fourth title wasn't originally a Silent Hill game, but that's moot. Now the US team Climax has taken the effort to bring the Silent Hill universe to the PSP with Origins, a tale preceding Harry's quest in the first game and meant to tie together the stories of the games and the story of the movie -- that is, focusing on Alessa once more."

Full Source: PSP Fanboy