How to change drive letter of DVD/CD rom

I recently reinstalled XP Home Edition OS on a Compaq Presario 8000 desktop and since then the CD-Rom and DVD/CD Rom drive letters have been switched. CD-Rom used to be “D” now it says “E” and DVD/CD Rom now says “D”. Is there a way to switch the drive letters back to the original config? Neither devices are fully operational at present. Thanks in advance for your help.