If you need to change you CD or DVD-rom drive to another letter, right-click on the My Computer icon and select 'Properties'. Click on the 'Device Manager' tab and expand the CD-Rom entry by clicking on the 'Plus' sign. Right-click on the name of the drive you want to change and select 'Properties'. Click on the 'Settings' tab and use the drop-down menus in the 'Reserved Drive Letters' section to select another letter for that drive (use the same letter for both entries). Click OK then reboot your computer for the changes to take affect.