Actually, I doubt you actually have two installations of XP on your
computer. I suspect that you have two entries in your Master Boot Record. To
"fix" the MBR follow this:

For FIXBOOT HELP, paste the followwing line into Start | Run and click OK...

hh bootcons.chm::/bootcons_fixboot.htm

FixbootWrites a new partition boot sector to the system partition. The
fixboot command is only available when you are using the Recovery Console.

For FIXMBR HELP, paste the followwing line into Start | Run and click OK...

hh bootcons.chm::/bootcons_fixmbr.htm

FixmbrRepairs the master boot record of the boot disk. The fixmbr command is
only available when you are using the Recovery Console.

<quote>
FIXBOOT
fixboot drive name:
Use this command to write the new Windows boot sector code on the system
partition. In the command syntax, drive name is the drive letter where the
boot sector will be written. This command fixes damage in the Windows boot
sector. This command overrides the default setting, which writes to the
system boot partition. The fixboot command is supported only on x86-based
computers.

FIXMBR
fixmbr device name
Use this command to repair the MBR of the boot partition. In the command
syntax, device name is an optional device name that specifies the device
that requires a new MBR. Use this command if a virus has damaged the MBR and
Windows cannot start.

Warning This command can damage your partition tables if a virus is present
or if a hardware problem exists. If you use this command, you may create
inaccessible partitions. We recommend that you run antivirus software before
you use this command.