Well, oddly, in WinXP, svchost mainly hogged all of the CPU when
checking for updates. This issue was "kind-of" resolved with SP3, but I
can't promise anything for Vista, but it's worth a shot... temporarily
atleast.

Turn off Automatic Updates if you haven't already, and maybe just check
for updates every now and then before you fall asleep. Seemed to work
for me for the longest time, but like I said... that wasn't Windows
Vista.


--
Zyonix