Back up your personal data and files onto some type of storage media, such as an external hard drive or a DVD. Fformatting will erase everything on the hard drive.
Gather all of the manufacturer driver discs that came with your PC hardware. For example, many video cards require additional drivers to enable advanced features.
Gather all of your software installation discs. Any programs or applications that you use will need to be reinstalled after you reset your hard drive.
Load the operating system installation disc into the CD/DVD drive and restart the computer. When your computer restarts it will ask you to press any key to boot from the installation disk. Press any key.
Choose to allow the operating system to format, and partition the hard drive with the default settings. If you are familiar with partitioning a hard drive, you can also choose to manually partition the drive.
Select a username and password when prompted. Setting up an administrative account is very important for security purposes.
Wait for the installation to complete. Remove the installation disc and restart the computer. Allow the operating system to load and then log in with your new account.
Install additional hardware drivers and programs using the installation discs you gathered.
Load your personal data and files into the new operating system from the external storage media.
Perform any Windows updates that are needed. Any Windows updates you performed since you purchased your computer will need to be performed again. To do these updates, click the Windows "Start" button, select "All Programs" and choose "Windows Update."