How to Change Hard Disk and CD-ROM Drive Letter in Windows XP

Click the start button then go the Administrative tools option.

In Administrative Tools, go into Computer Management option then click on Disk management under Storage option.

Directly Your Can Open Disk management By Using Run Command diskmgmt.msc

Here in lower right corner you will option to change.

Option from the "assign the following drive letter", select the letter you want to assign to the hard drive or the cd-rom drive then click Ok.