Use the Disk Cleanup Tool in Start/All Programs/Accessories/System Tools.
There is an option in that tool to remove this file.
"Dell Palmer" <DellPalmer@discussions.microsoft.com> wrote in message
> When I upgraded to Vista a directory called windows.old was created which
> contains my old windows xp system. Is there any reason I can't delete this
> directroy? It's taking up needed space on my computer.
> Dell Palmer