Minimum System Requirements:

*CPU: P4 2.8GHz (3.2GHz Vista)/Athlon 64 3000+ (3200+ Vista)
*GPU: DX9-capable graphics card with 256MB (SM 2.0b). NVidia 6800 or ATI X700.
*RAM: 1GB (1.5GB Vista)
*Hard Drive: 12GB
*OS: Windows XP SP2/Vista SP1
*DirectX: 9.0c
*Sound: DX9.0c compliant
*Optical drive: DVD (boxed only)
*Internet: Broadband

Recommended System Requirements:

*CPU: Core 2 Duo 2.2GHz processor family/Athlon 64 X2 4400+ (required for MP host)
*GPU: Fully DX9-compliant graphics card with 512MB (SM 3.0). NVidia 8600 GTS or ATI HD 2900 XT.
*Ram: 1.5GB
*Hard Drive: 12GB
*OS: Windows XP SP3/Vista SP1
*DirectX: 9.0c
*Sound: DX9.0c compliant
*Optical drive: DVD (boxed only)
*Internet: Broadband (768kbit/sec upstream required to host 16 players)

http://pc.ign.com/articles/944/944021p1.html

The game runs quite well on my Vista rig with a single 8800 GTX, 4GB RAM and a 3.0ghz Dual Core 2. It ran at 60 FPS for the most part, with it dropping down to only about 40 FPS in a few areas, but since the game is so dark it’s really hard to notice. (Your flashlight doesn’t do jack…a cellphone could provide better light.) You can now hold up to four weapons. You still have you’re slow-mo ability, but it has drastically changed, both good and bad. For one, targets now light up in an almost psychedelic way. However, the speed of your slow-mo doesn’t seem to be as slow anymore, and the audio cue when you activate and deactivate it isn’t as loud, so it’s a little hard to tell if you have it active on or not. Also Q and E no longer makes you lean, (in fact there is no more leaning) in favor for a weapon-function change, and an all purpose “use” key, repsectively. Lastly, the game doesn’t seem to support widescreen resolutions very well. Although you can change to such resolutions, the game shows it in letterbox format. C’mon guys, it’s 2009, get with the times. You can’t even buy a regular TV anymore.

Oh yeah and theres a cool mech armor thingy at the end of the demo you get to use. Other than that, that’s about all that’s changed, as far as the demo goes. Combat is still great, AI is still clever, scares are still plentiful (and better with the new graphics) but more or less it’s prettty much the same game. Whether or not this is a good thing is up to you, but I’d say this is the first true sequel to the original, as the name implies. We’ll see how the full release goes.