Multi-booting program caused boot problems

A friend tried to set up a multi-booting program (System Commander, I think) on a 40gb hard drive. He tells me that he got XP installed OK but when he tried to add Vista the whole thing turned to custard.

I've tried to format the drive and reinstall XP but it goes nowhere, ie it appears to accept the install command, formats the drive in NTFS then starts copying files, but just keeps returning to the start of that process.

I thought that the multi-boot app might have modified the mbr, so I ran the recovery console, then the command "fixmbr ". It said it had found a non-standard mbr and asked me to confirm that I wanted to write a new one, which I did.

It still seemed to be acting strangely so I repeated the process and ran "fixboot ". Then I tried to load XP again but it's still looping and not completing the install.

Is there any other way of getting the drive back to a basic state that'll accept a Windows install? Like writing zeros, for instance?

Thanks