Resident Evil 4 HD is out on Steam today! YouTube user Space Sharkicane (what a name) ran through the new PC version and compared the same scene with the PS2 version of the game. Take a look!
The first run through the scene is on PS2 at 480p (scaled up to match the HD video). The second run through is on the new PC version. You can definitely see a difference in the graphics, but where the HD version really shines is in the audio.