HDD problem (very slow and shows some errors)

HDD problem (very slow and shows some errors)
I have a WD hard disk - 640 GB. It got pretty full, so i decided to put in another hard disk (maxton - 80 GB). The first one uses SATA and the second one ATA. I connected the second one on a same cable as my dvd rom (dvd master, hdd slave).

My system became very slow, and that hard disk i added is slow as well. Sometimes it opens, sometimes it doesn't, i get "cyclic redundancy check" errors or "The request could not be performed because of an I/O device error". And now i got The "Drive H:/ is not formatted" error.

Is this a file system error or is my hard disk dying?

I'm using Windows XP SP3.

(maybe it's important - i used that hard disk on my old computer, and when i bought a new computer, i left the old one in the old computer (OS wasn't installed on it). It has like 4 GBs of somewhere 80GB (it always less than specified).

 

Determine the brand of each hard disk.

Download the disk manufacturer's testing utility for each one.

Run extensive tests on each disk.

If they come up okay, then it is s file system problem.

Run CHKDSK x: /R on each disk, where you substitute your drive letter for the "x".

When you run it on the C drive, it will say it cannot run because the drive is in use. Ansyer "yes" and restart the computer.