To upgrade from Windows XP to Windows 7, boot the computer from the Windows 7 installation disc, and initiate a custom installation process to overwrite the partition that contains the Windows XP files. Before installing Windows 7, backup personal files manually or by using the Windows Easy Transfer utility.
Put the Windows 7 installation disc into the optical drive, and restart your computer. If the setup process doesn’t start automatically, enter the BIOS setup screen by pressing the key that appears as part of the BIOS access message while the computer is booting up. Then, locate the Boot Order section, and set the optical drive as the primary boot option.
Once the Install Windows screen appears, select the Custom option, and select the hard drive or the partition that houses Windows XP. Then, click Next to start the formatting process, which can last up to 30 minutes depending on the size of the hard drive and the speed of the processor. Once the formatting and installation processes finish, type the product activation key for Windows 7, and select a name for your PC, setting a password if necessary. If you’re connected to the Internet, click on Use Recommended Settings to allow Windows 7 to automatically download security patches and updates. After completing the initial setup, transfer the files you backed up earlier, and reinstall any necessary software.