Removable Device Drives

By the looks of those icons you have XP?

To change drive letters

Goto Computer Management, their are two ways to do this easily either Right Click My Computer > Manage > Disk Management or Control Panel > Administrative Tools > Computer Management > Disk Managment

then once there... highlight the drive in the top right hand window and right click it, your given some options one is to change Drive Letters and Paths, choose this to change the drive letters then choose Change, next to Assign the following drive letter is a drop down box use this to change the letter to the ones you want ( DO note than you cannot change a letter to one you already have allocated, first you will have to put the drive letter your wanting to change to, to one such as X,Y,Z as this then will free up that drive letter to be used )


above taken from an old post of mine but should cover your question.

If you have an inbuilt digital media card multi reader then that could also be linked to those devices, they generally list removable drives like that.

 

Also, I left out an important bit as you were not talking about the HD/partition letter the OS is on, but thought it still worth a mention...

DO NOT change the drive letter the OS is on as it will cause you to re-install Windows.