Direct2Drive's Call of Duty: Black Ops Listing shows PC specifications for the upcoming military shooter sequel (thanks Eurogamer). They don't have recommended requirements, but the minimum specs follow.

Call of Duty®: Black Ops Download Minimum System Requirements

• OS: Windows® Vista / XP / 7
• Processor:Intel® Core™2 Duo E6600 or AMD Phenom™ X3 8750 or better
• Memory: 2GB
• HDD:12GB**
• Video: Shader 3.0 or better 256MB NVIDIA® GeForce® 8600GT / ATI Radeon® X1950Pro or better
• Sound: DirectX 9.0c-compatible
• DirectX: 9.0c

** There is no footnote corresponding to these asterisks.