"There are two ways that disk drives get drive letters on a PC. The first kind are the ones controlled by your BIOS. These usually include your floppy and most hard drives, for which drive letters are created when your system is first turned on. The second kind of drives are controlled by software, or more specifically, drivers. These types of drives include CD-ROMs, Syquests and other removables, network drives, and sometimes SCSI hard disks with ID's other than zero (0) or one (1). Generally, drive letters are assigned to these drives depending on the order in which they are loaded.
For Windows 2000/WinXP:- Open the
Disk Management console (diskmgmt.msc) by right-clicking on
My Computer- Right-click on any drive, and select
Change drive letter and path.
- Windows will let you know if the drive letter cannot be changed for some reason.
For Windows 95,98, and Me:Windows 9x-Me only allows this configuration for those drives controlled by drivers (the second type mentioned above). By editing the Registry directly (see Solution #2 below), you should be able to change the drive letter assignments for any type of drive. Note: It is extremely important that you back up your Registry before continuing."
The above and the rest of the procedure is here:
http://www.annoyances.org/exec/show/article02-024Dell