Yes, you can do multiple backups to an external drive, thats how I do mine.
Just make sure that the machine names are not the same since the backup will
be renamed after your machine in a folder.
--
Andre
Blog:
http://adacosta.spaces.live.com
My Vista Quickstart Guide:
http://adacosta.spaces.live.com/blog/cns!E8E5CC039D51E3DB!9709.entry
"T Sickles" <(E-Mail Removed)> wrote in message
news:%(E-Mail Removed)...
> Is it possible to backup multiple computers running vista to one external
> hard drive or will one copy overwrite the previous?