Yes, the first one you do is a full backup.
You will also do a full backup if you delete the Windowsimagebackup dir.
If you leave this dir intact & performa backup, only the changes since the
last backup will backed up.

I always leave the dir intact, at restore it will restore your latest
backup.
I've seen nothing to suggest that deleting the dir each time is worthwhile.

"Rwhit78" <Rwhit78@discussions.microsoft.com> wrote in message
news:75A1276F-4AD8-4736-B31A-FC44830056EE@microsoft.com...[color=blue]
>I can't find much technical information on using full backup under Vista. I
> am using an external hard drive for backups. Am I right in thinking that:
>
> a) if you do a 'full' backup repeatedly to the same external drive, the
> first time it will be a real full backup whereas later ones, though still
> called 'full', will in fact be incremental?
> b) if you delete the 'WindowsImageBackup' directory from the external
> drive,
> will force the next full backup to be truly 'full' again (not
> incremental)?[/color]