XP Pro upgrade to what? I assume you tried to install SP2 to Home Edition,
you discovered the problems you mentioned and then tried to install XP Pro
from an upgrade disk. You cannot upgrade from Home Edition with SP2 to XP
Pro with no service pack.
If you can't boot the system to the desktop, it would appear your setup is
totally hosed, the only way out is to start over clean, meaning you'll lose
everything on the drive. Depending upon the type of disk you have for your
original OS, assuming it was XP Home Edition, if you are not backed up, you
can try installing XP to a separate partition, then copy your data from the
previous setup to the new one. If you have no such available partition, you
would need third party software such as Partition Magic,
www.powerquest.com
to first create such partition by resizing the current partitions, creating
free space and then creating a new partition, then run XP setup by booting
from the CD as follows:
Assuming your system is set to boot from the CD-ROM drive, boot with the XP
CD in the drive. If it isn't or you are not sure, you need to enter the
system's BIOS. When you boot the system, the first screen usually has
instructions that if you wish to enter setup press a specific key, when you
see that, do so. Then you will have to navigate to the boot sequence, if
the CD-ROM drive is not first line, set it first in the boot sequence. Save
your settings and exit with the XP CD in the drive. The system will reboot.
A few screens into the boot process, if you see the message on the boot
screen to "Press any key in order to boot from the CD," do so.
After loading drivers and files, you should be taken to a screen with
the following:
To Setup Windows XP now, press ENTER.
To Repair a Windows XP Installation using Recovery Console press R.
To Quit setup without installing Windows XP, press F3.
In your case, press ENTER.
Agree to the License agreement by pressing F8.
You will then be taken to a screen with two options.
To repair the selected Windows XP installation press R.
To continue installing a fresh copy of Windows XP without repairing,
press ESC.
This will bring you to a partition map where you
can delete, create and format partitions.
Select the drive you wish to format, delete the partition, then create a new
partition, format as desired and continue with XP installation.