WU TEMP - configuration help

i've partitioned my 80gig h/d as follows:
c:winxp; d:temp; e,f,g:files

i've set tmp and temp directories as d:\usertemp and
d:\wintemp, as well as moved the paging file to d: (by
changing the settings in the systems under control panel)
so as to minimize defragmentation on c: and for easy
maintenance -- i only have to defrag d:

problem: whenever windows does updates, it creates a
temporary folder called wu temp (i supposed it stands for
windows update temp) on my last drive - g:.

like i mentioned before, i want to minimize defrag on
multiple drives. that's why i moved them all to d:

i don't want windows update to create the temp folder in
g:. anyone know how to set this so that it will create
the folder in d:?

i've searched for the string "wu temp" in regedit but
didn't find any. am i searching for the wrong string?