Are you offered an option to boot from? If so the BOOT.INI file will need editing
"How to Edit the BOOT.INI File in
Windows XP" click here
This basically involves going to Control Panel, System, Advanced, Startup and Recovery, Settings. In
the System Startup section, click the Edit button. This will bring up
BOOT.INI. You could post the results here if you're concerned.
You can delete anything you wish off of the installation you want to kill, with the
exception of NTLDR, NTDETECT.COM and BOOT.INI.