i played cod4 on the computer.. there wasnt any problem with fps drops back then.
black ops runs low the majority of the time.. the fps dont jump up to max very often at all, unless you are inside a building with your nose in a corner.
it doesnt sound like what the rest of the world has seen in the past.
cod4 should be running at max with some dips based on screen activity.
maybe you run some benchmarks to see if your scores are normal.