gregebowman, it depends on which OS you have. In WinXP/2000, in Administrator mode, go the the Administration Tools under Setting, Control Panel, select Computer Management, then Disk Management under Storage. In the lower window, scroll down the list of drives until you get to the CD-ROM drive you want to change. Right click on it and select the "change drive letter" option. You don't have to reboot.
Under Win 95/98/SE/ME, you have to do it though the hardware config management screen. Right click the "My Computer" icon, select Properties, select the Hardware tab, look for the CD-ROM drive and right click on it. Select Properties and I believe you can change it there if I remember right. You may have to reboot.
If you have a CD Writer like I do, and just use it to burn disks and not to install software from, this is a pretty safe option. If you have only one CD drive, changing the mapping will screw up all the applications that you installed from that drive that require a CD in the drive to run.
Good luck, hope this helps, I feel your pain. I'm having a bLast playing the game at long Last.
-ColdSteel