Removing Vista and reinstalling XP... how to do it?

Hello

I have an older PC running an eval of Windows Vista and I now want to put my
licensed copy of XP Media Center Edition back on there.

The obvious route was to boot from the XP CD, run install, and delete and
reformat the partition that had Vista on it and install XP in the new
partition.

However when I do this, upon next reboot during XP install, I simply get the
message "Error Loading Operating System".

I have heard that Vista mucks with the boot sector in some way such that
this happens.

The question is how can I wipe the last traces of the Vista stuff from my
hard drive so I can reinstall XP.

Note: I already deleted the Vista partition, reformatted it (quick format).
There is only one drive and one partition, FYI

Thanks in advance
SS