Here are the minimum system requirements for running Call of Duty: Black Ops on a PC:OS:
Windows® Vista / XP / 7
Processor: Intel® Core™2 Duo E6600 or AMD Phenom™ X3 8750 or better
Memory: 12 GB free hard drive space / 2GB RAM
Video Card: Shader 3.0 or better 256MB NVIDIA® GeForce® 8600GT / ATI Radeon® X1950Pro or better
Internet Connection Required
Notice: The product offered is subject to your acceptance of the Steam Subscriber Agreement ("SSA"). You must activate this product via the Internet by registering for a Steam account and accepting the SSA. If you do not agree with the provisions of the SSA, you should return this game unopened to your retailer in accordance with the retailer's return policy.