My 80 gb hd is a new one. It has 4 drives, each one with 20 gb each.
One day while scan disk there were bad clusters in drive c: .
I removed the partition of c: drive and formatted that drive.
Few days after formatting, bad clusters were again found in drive c: .

Now what should I do.. shall I remove all the partition and format it again ? Or simply go to the doctor ?

First, lets understand what bad clusters are. A hard drive is a set of thin plastic platters coated with magnetic material. The platter is divided into sectors that contain areas that hold a positive or negative magnetic polarity. These correspond to computer bits and represent the 0s and 1s of the binary numbering system. When a sector loses enough of its coating that it may no longer be able to hold its polarity its considered a bad sector.

Bad sectors are not abnormal and can occur on any drive, even a new one.

Second point, you have ONE physical drive which is divided into 4 PARTITIONS that are formatted as logical drives.

Now the question of what to do about bad sectors. Formatting was not necessary. Depending on your version of Windows, you would either use Scandisk or Chkdsk to deal with bad sectors. What either does is analyze each sector for the strength of its polarity. If it finds a sector where the magnetic strength is below a safe threshold, it moves the data from that sector to another sector then marks the sector as bad so its not used.

Again, bad sectors are not uncommon. Up to 10% bad sectors is a permissible level. So after you have run Scandisk or Chkdsk, you want to run either on a regular basis (weekly) for awhile. If no new bad sectors are found, then your disk is fine. However, if more bad sectors continue to appear, then your drive is failing and needs to be replaced.

Formatting was not the right procedure because formatting may not detect the bad sectors as well as Scandisk or Chkdsk. So it might not have marked the sectors as bad and the same secotrs turned up as bad again.

Yea I think you are right, formatting was not necessary.

Actually what happened was that, the scan disk found around 12 bad clusters and replaced them, the scan disk took a long time.. it first checked the files and folders on c: drive and then it checked for free space. The machine was freezed, and a time bomb like ticker noise was going on in the CPU. I think that tick noise was coming from the hard disk.
After that when I restarted the machine, it again scanned drive c: and again it freezed. I was forced to remove the partition of drive c and then format it.

Aftet formating the machine was good for few days, just yesterday there was scan disk of drive c: and it found around 12-15 bad clusters and replaced those, everything that happened later on was similar to the first one.

What I did now is that I formatted the whole system, made all the partition again,

I have norton disk doctor and partition magic with me, shall I try these ones out ?

Try Disk Doctor which is a souped up version of Scandisk.