Welcome to Windows Seven Forums.
The first thing you need to do is get an external hard drive and backup all your important data to it.
Then you need to contact Dell support with a view to getting the hard drive replaced while your laptop is under warranty.
http://supportapj.dell.com/support/i...=in&l=en&s=gen
The clicking noises and overheating are sure signs that the hard drive is about to expire. You may need to change the region in the above link if I've got it wrong - I've assumed you live in India.