Gary,
My laptop does not wake from sleep, but then it is XP so not really apropos.
My desktop (Vista) does wake itself up from the hibred/sleep mode to perform
various tasks. It then goes back to sleep.
It is certainly possible that the DellCrap that was preinstalled on your
computer is updating stuff or phoning home.
Waking up from sleep is a purposeful feature of Vista. However some people
hate it. There are many threads on the groups with subjects like 'laptop
wakes up' 'won't stay asleep' etc. Unfortunately those threads seem to
attract a lot of trolls and MS haters. Be carefully what advice you take
from these threads as you can end up with a damaged system.
On my Vista XPS410 desktop I only have one task in Task Scheduler that is
set to wake the computer, that is RoxioUpdater.
You can go through each task in the Task scheduler to see if any there are
set to wake the computer. You need to click on each folder in the left pane,
then if any items show in the top middle pane select them one at a time and
look in the lower middle pane Conditions Tab, under power settings is 'Wake
the computer to run this task button'
Programs CAN schedule themselves without listing in the task scheduler so
this won't find them all.
Michael