Question : Windows Upgrade Failed. How can I cancel installation?

Please, help me!!!!!!!!!!!!!!!!!
I had to reinstall Win XP Home Edition SP2 after cleaning virus. I used setup files on my hard drive. During upgrade it asked me to provide different files (I guess drivers). I thought all files are supposed to be already Installed because I was doing just upgrade not a cleam install of Win XP.   After installation portion on finalizing, setup failed with blue screed BAD_POOL_HEADER. I restarted my comp. The Installation went back to preparation portion. And again on finalizing setup failed.
Is there the way to cancel this install and go back? How can I do this? I need to be able to load Windows XP.
Thank's
PS I have NTFS

Answer : Windows Upgrade Failed. How can I cancel installation?

You need to remove/disconnect all external peripherals except the monitor, keyboard and mouse, and be sure those are not USB, or wireless.  Any internal USB card should also be removed.