If you have been thrashing the hard disk with various benchmarks, you can expect it to get hotter. Older hard disks also tend to run hotter. However, imho 57 deg is a bit beyond reasonable even in such circumstances. Can you move the hard disk to another bay with some more clearance around it?
Apologies, should have read the fine print... 57 deg is too high even for a laptop. I had a Toshiba Satellite Pro 6100 which had the hard disk above the RAM due to which the hard disk was at 55-56 deg at idle and was reaching 60 deg with high activity. That laptop went through three 60GB hard disks before I decided that enough was enough and changed it.
HDtune?