Drive assignment?

A friend asked me to help him with a new Omega external drive. He added this to allow him to take work home. When he pluged into the USB at work the drive came up as D: and his CD is always F:. At home the new drive came up as F: and the CD is D:. This caused him to change the path parameters in the program he is using each time he moves the drive. I checked the comfig.sys for an entry for the CD at his work pc and there is none. How does the work pc assign the F: drive to the CD?

 

Open Device mangler, select the Drives, and expand the + beside, select the CD in question, right click, select properties.
Somewhere in there, you can designate it to become drive F, which will free up D for use of the IOmega.
Plug in the Iomega drive, and assign it to D.
Now it should stay that way, and allow you to use it on both machines without messing any more in the program settings.