Your problem can be easily resolved in one of two ways.
1- Boot the computer with a Windows 98 boot diskette and issue the
FDISK /MBR command on both the old 80GB IDE and the new 250GB SATA hard
disks. Then, as an added precaution, disconnect (or disable in the
BIOS) all but the 250GB SATA disk and boot the computer to the new
Windows XP installation on the SATA disk. Issuing the FDISK /MBR
command on the disks will rewrite the disk signatures and the
information for these disks in the Mount Manager's MountedDevices
database will become invalid, the drive letters will have to be
reassigned. When the computer is booted the I/O Manager will reassign
drive letters based on a set of predetermined rules, one of these rules
being that the first active partition will be issued drive letter C:.
The first active partition is usually the one used to boot the Windows
installation but when both IDE and SATA disks are present the IDE disks
may be enumerated before the SATA disks, disconnecting or disabling all
but the 250GB SATA disk will eliminate any possibilities of the active
partitions on IDE disks obtaining drive letters before the SATA disk.
After the first reboot (with the SATA disk only) you can shutdown the
machine and reconnect or enable the other disks again and reboot the
computer, the other disks will be reassigned other drive letters, these
letters on the non-system/non-boot drives can then be changed by the
usual methods if you want.
2- Go in the registry and delete *all* the entries in the
MoundedDevices key, do not delete the key itself! The information in
this key is also known as the Mount Manager's database. Then, as in the
first method above, disconnect or disable all but the SATA disk and
reboot the computer. Without any information in the Mount Manager's
database all disks will be treated as new disks and, as stated earlier,
the I/O Manager will reassign drive letters based on a set of
predetermined rules, one of these rules being that floppy drives will be
assigned letters starting at letter "A:" and another rule being that the
first active partition will be issued drive letter C:. As mentioned
earlier, after the first reboot you can bring the other hard disks online.
Either of these methods should fix your drive letter problems. I would
opt to delete all the information in the Mount Manager's database, it
will cleanup the key of any invalid entries and in my opinion it is
faster and easier than using the fdisk /mbr method. If you are unsure
or wary about registry editing then use the fdisk /mbr method, the end
results will be the same. While using the fdisk /mbr method may leave
some invalid or orphaned entries (clutter) in the MountedDevices key
please note that these unused entries will in no way whatsoever affect
the newly assigned drive lettering, the Mount Manager will ignore the
invalid entries.
John