Is it normal for Hard Drive to make some noise while working?

It all depends, the first thing i WOULD do is defragment your hard drive, if it is 85% full and you hven't done that it can actually wear the drive down faster as it has to search for everything. Once you defragment it you should see a difference in speed as well as make it easier on the hard drive. The drive making noises are also a sign that it is about to go out, but that depends on how old it is. If it's a few years old i'd back stuff up and get a new one, you can get a 1TB drive for around 100 bucks at best buy these days. or go to tigerdirect.com for other deals, from the sounds of it though, it may be the way hitachi builds thier drives if both of yours have done this.