I want to share this solution with the rest of the NG.
Problem: Win 7 goes to sleep and wakes up almost instantly or in a couple of
minutes.
Solution: Device Manager, Nework Adapter, Properties, Power Management,
Uncheck "Allow this device to wake up..."
Though it is quite obvious, it took me almost two weeks to get there after
playing with settings in the power plan, and disabling mouse/keyboard ability
to wake up the pc from sleep (same option in device manager, but in mouse and
keyboard entries, respectively).
It seems that Win 7 enables the Network Adapter to wake up your PC by
default. For me this is a new behaviour that I had not found in pre-Win 7
Windows (Vista and younger) and that's what made me look elsewhere.
I am not alone, as many others in the Win 7 Technet forum
(
http://social.technet.microsoft.com/...tegory/w7itpro) are also
having this issue.
If you want to see which devices are enabled for waking up your current
configuration just run
powercfg -devicequery wake_armed
from a command prompt window.
Hope this helps if someone "cannot sleep". This one is Valium-free.

Carlos