You cannot change the system volume drive letter after Setup

After Windows The Setup program is finished, you cannot change the drive letter of the system where Ntldr resides or where the boot volume (%Windir%). The drive letter of the hard disk on which Windows is installed is hard-coded in the registry. If you change this the drive letter, programs in the "Program files" directory may not run correctly because the registry may have pathing to the old drive letter. Changing these drive letters by using any tools or by modifying the registry is not supported.

IIn Windows, you can reassign the drive letters associated with drives after Setup runs, but not for the system or the boot volume.

If you try to use the Disk Management console to change the drive letters of the system or the boot volume, you receive one the following error messages:
Note The boot volume is where the \Winnt folder is located, the system volume is where the boot files (boot.ini, ntdetect.com, etc.) are located.

When you are installing Windows 2000 using Winnt32.exe, you can specify the folder in which Windows should be installed by clicking Advanced Options. This option is available only when you are performing a "clean" installation of Windows.

A "clean" installation of Windows 2000 means either installing Windows 2000 on a blank hard disk, or installing Windows 2000 in a folder other than the folder in which an existing version of Windows is installed.