Do you have a Snow Leopard DVD? Is your computer capable of running the version of Snow Leopard you have?
Clean Install of Snow Leopard
1. Boot the computer using the Snow Leopard Installer Disc. Insert the disc into the
optical drive and restart the computer. After the chime press and hold down the
"C" key. Release the key when you see a small spinning gear appear below the
dark gray Apple logo.
2. After the installer loads select your language and click on the Continue
button. When the menu bar appears select Disk Utility from the Utilities menu.
After DU loads select the hard drive entry from the left side list (mfgr.'s ID and drive
size.) Click on the Partition tab in the DU main window. Set the number of
partitions to one (1) from the Partitions drop down menu, set the format type to Mac
OS Extended (Journaled, if supported), then click on the Partition button.
3. When the formatting has completed quit DU and return to the installer. Proceed
with the OS X installation and follow the directions included with the installer.
4. When the installation has completed your computer will Restart into the Setup
Assistant. Be sure you configure your initial admin account with the exact same
username and password that you used on your old drive. After you finish Setup
Assistant will complete the installation after which you will be running a fresh
install of OS X. You can now begin the update process by opening Software
Update and installing all recommended updates to bring your installation current.