Reinstalling O/S w/o Formating

[Saber]

Spock or anybody else, You really can reinstall win XP Home or Pro without Formating and keep everything already on Hard drives?

[Spock]

If you reinstall the original OS without formatting the HD, it should simply ensure that any missing programs or other necessary files are restored and reset the register links required to operate properly. The catch is that, with newer Operating Systems, you will need the CD/DVD registration number for the OS you are trying to reinstall and if it isn't the exact same disk s was originally used by the OEM it may not work anyway.

Here is a Webopedia article on How to format a Hard Drive that may help.