For black ops you will need windows which is about $100 iirc you can get it cheaper if you are a student. I said this wasent a gaming rig but black ops is really well opitimised so you may be able to get 720p on low to mid.
The intention of the rig however is more to be as cheap as posible rather than a gaming rig with that in mind my list is also intended to be cheap as posible so get MSI FM2-A55M-E33 instead and then:
OS Linux - Free (Lately there has been a bunch of awesome indy games that you can get for linux but black ops wont run)
Keyboard and mouse - $20 to get a shitty combo.
Monitor & speakers - Use an hdmi cable to plug it up to your tv.
Network cable - Probaly got one with your router.
Dont need thermal paste and your mobo should come with sata cables and psu with a power cable other than that you dont need any cables except for perfarials.