H: I have a dell d600 and the hard disk below the palmrest is getting hot how i resolve this problem

Overheating of harddisk is very common in laptops.
But it can cause problems. So i suggest you to clean all the vents, get the heatsink cleaned or replaced at service center. Also you can decrease the spindown time of harddisk to minimize its usages...
for changing spindown time go to..Control Panel>>>All Control Panel Items>>>Power Options>>>Edit Plan Settings>>>click change advance power settings>>> in advance reduce the turnoff harddisk time to 1 Minutes.

hope this will help for sure.....cheers