I recall a trick whereby one formats a hard drive to a smaller space so the heads did not have to move so far.
I have a story to tell.
I used to use a 36 gig raptor (which by the way works fine today, very high quality built drives).
I then decided I needed more space, so the choice was the new 72gig raptor, or a WD black 640 gig (this also still works). In those days WD blacks were very well built drives as well inheriting a few features from raptors.
I ultimately decided to buy the 640 gig, I made a 40 gig partition at the start, which basically meant for the OS it was assured the use of the fastest part of the disk which gave it access times only slightly worse than my old raptor, and throughput in excess. Of course the performance on rest of disk wasnt as good but I treated it as a fast OS disk, and a bonus slower extra 600 gig disk tacked on. Great decision.
It was also a well known tweak to make a dedicated partition for a swap file, to ensure it wasnt competing for sectors with anything else (no fragmentation) and assurance to be on faster part of disk.