So my question is how quiet the 7200.7 is and should I care, my system with the loud cooling needed for the p4 2.8c.
*gasp* "Should I care?"
Of course you should care about the noise.
Have you already seen Dru's Seagate Barracuda 7200.7 HDD Review
from the main site? If not, it would be a good starting point to answer your question.
I don't have experience with the 160GB drive, but multiple drives will raise your noise table and multi-platter drives are louder than single platter drives. But we can't all get along with a single-platter 'Cuda or Samsung.
The other articles in the Storage
section of the main site will have ideas on suspending, boxing, sandwiching, etc. the drive for further quieting.