I wouldn't even consider RE4 to really be Resident Evil, to be honest, since that's when the shift from slower, more methodical survival horror to kill-'em-all action first happened (though even by Nemesis the series was getting there). Having played pretty much every RE game released for a PlayStation, including spin-offs like Outbreak and Survivor (*wince!*), RE2 is
still my favorite of the bunch.
RE4 is widely thought to be one of the best action-horror games ever released, though, and I'd have to agree with that sentiment.
PS3 players can check out the first three RE games, as well as Dino Crisis and Silent Hill 1, as $6 downloads ($10 for RE1) on PSN. But obviously the visuals, and especially the controls, are going to seem pretty dated by today's standards! It's great, though, if you still wanna pick one of them up from time to time while retiring your original discs (*cough*RE2*cough*).