Your question: re-install to the same directory.... you can perform a repair re-install that will not touch your progs. I had a quick look at your link and lost the will to live so if this has been covered already then apologies....
Boot the computer using the XP CD.
When you see the "Welcome To Setup" screen, you will see the options below
This portion of the Setup program prepares Microsoft
Windows XP to run on your computer:
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.
Press Enter to start the Windows Setup.
Do not choose "To repair a Windows XP installation using the Recovery Console, press R", (you do not want to load Recovery Console).
Accept the License Agreement and Windows will search for existing Windows installations.
Select the XP installation you want to repair from the list and press R to start the repair.
Setup will copy the necessary files to the hard drive and reboot. Do not press any key to boot from CD when the message appears. Setup will continue as if it were doing a clean install, but your applications and settings will remain intact.
You will not loose any progs but you will have to Reapply updates or service packs applied since initial Windows XP installation.