Reinstalling factory OS-errors

I am no computer genius, but a senior citizen asked me to help him with his computer. There were a ton of viruses on his system. It was an HP with a Quantum HD. The original software was Win2k, but had been upgraded to XP sometime before he received the computer. When I tried to reinstall the factory disks from HP, it couldn't be done. I tried to utilize the fdisk utility to wipe the drive. when i try to run the recovery CD's-all goes well during the initial screens-I receive the warning message saying "Procedures in the next menu can erase programs and/or data on your HD" I select OK. It gives me a menu 1)recover 2) About 3)Exit. I selected recover. Brings me to a second menu 1) format/recover 2)recover only 3) cancel. I select format and recover. I receive a warning message stating that PC will be restored to factory state. The system starts to unpack and restore the files..but during this process, I receive the following message:

Finished recovering files. **Warning** recover ran out of disk space while recovering files. Remove the CD and press ok to reboot your machine. I reboot the machine. I get a windows Mellinum start up menu with the following message:Windows has detected a registry/configuration error. Use SCANREG to correct this error.