Some details have finally been released for the up and coming Dark Souls: Prepare to Die (due August 24th), so you can see if your PC is ready to meet the challenge.
OS:Windows XP , Windows Vista, Windows 7, or newer
Processor: 2.6 GHz Dual-Core
Memory: 1 GB (XP), 2GB (Vista/7)
Hard Disk Space: 4 GB
Video Card: 512 MB RAM, ATI Radeon 4850 or higher, NVIDIA GeForce 8800 GT or higher
Sound: Direct Sound Compatible
Also, the game will not support in-game chat, which is good news for the Dark Souls lonely and punishing atmosphere.