Perhaps this will help you with the definition of "what is SATA?"
Its NOT a WWW.
address but cut and paste the address into your internet browser and it goes. (i tried it myself.)
As for RPM, I always thought it meant revolutions per minute.
And for using 1/2 of the hard drive, It is my opinion that you would not notice a difference in computer speed.
My other advice on this would be to get a hard drive with an 8Mb buffer if yopure in the market.