Re: installing an operating system on hard disk

HI

you can make clean install of OS in your system..through Recovery DVD's through Recovery Partition and Through Clean Install..

if you want to make a  installation through Recovery dvd then Follow

http://h10025.www1.hp.com/ewfrf/wc/document?cc=us&lc=en&dlc=en&docname=c01867418

if you want to make a clean install of your OS then first try these steps

 Download the ISO file for the version of Windows 7 you own:

• Home Premium SP1 (English, 64-bit)
• Professional SP1 (English, 64-bit)
• Ultimate SP1 (English, 64-bit)
• Home Premium SP1 (English, 32-bit)
• Professional SP1 (English, 32-bit)
• Ultimate SP1 (English, 32-bit)

for more information

http://www.youtube.com/watch?v=mME9VLT7-xw

if you have original windows 7 in your laptop then you can recover  your key through Magical Jelly Bean Keyfinder to pull your product key from the Registry. You need your product key to reinstall Windows.

or its written on 

Hope it works ..

still need help then ask it..