Hi, Kavi.
As Rick Rogers said, it was caused by your HD configuration at the time you
installed WinXP. The most common cause of getting a drive letter other and
C: is that a second HD, containing an Active "bootable" primary partition
was connected at the time WinXP Setup was running. And, as he also said, it
ain't easy to fix - unless you consider starting over easy.
Be sure that ONLY your new HD is physically installed and enabled. Boot
from the WinXP CD-ROM and follow the prompts, including the early one to
repartition and format at least the System Partition (and, if different, the
Boot Volume). After WinXP is up and running, shut down and install any
additional HDs. Then reboot, find the built-in utility Disk Management and
use it to create, format and otherwise manage any additional volumes you
need.
Disk Management (type diskmgmt.msc at the Run prompt) can do just about
anything you need done to your drives, but it cannot change the letters of
your System Partition or your Boot Volume. The only good way to do that is
to reinstall.
RC