To assign a drive letter to a network computer or folder
Open My Computer
On the Tools menu, click Map Network Drive.
In Drive, select a drive letter
In Folder, type the server and share name of the computer or folder you want.
Click Browse to find the computer or folder.
To open My Computer, click Start, and then click My Computer.
To reconnect to the mapped drive every time you log on, select the Reconnect at logon check box.
Mapped drives are available only when the host computer is available.
Network drives are assigned letters from Z to A, and local drives (your hard drive and removable storage devices) are assigned letters from A to Z.
You can assign a computer or shared folder to a different drive letter by disconnecting from the drive and then reassigning it to a new drive letter.