Sending our digital video recorder to sleep

Today I finally figured out how to get our Home Theatre PC (a home-built digital video recorder running Windows Vista Media Centre) to send itself to sleep correctly.  Prior to figuring this out, the system would stay on indefinitely in the situation where you're watching TV, you press the "off" button on the remote control but the system is recording a programme (the desired behaviour in this situation is to automatically turn off after it's finished recording but it would just stay on indefinitely).

The solution was actually really obvious and I'm somewhat ashamed I didn't figure it out previously.  All that's required is to go to Control Panel > Power Settings and set the system to suspend after a few minutes (it was previously configured never to suspend).

The HTPC draws 60-70 Watts when awake and 3 Watts when sleeping.

My measurements, prior to figuring out how to turn it off properly:

•  average for a 24hr period (measured over 50 hours) = about 0.6kWh per day
• = about 220 kWh per year
• = about £40 per year (at 18p per kWh)
• = about 118 kgCO₂ per year

After configuring it to shut down correctly, the stats are:

• average for 24 hours period (measured over 42 hours) = about 0.47 kWh per day
• = about 170 kWh per year
• = about £31 per year
• = about 93 kgCO₂ per year
• a 25% saving (not bad for two minutes' work)

So, from these (rather short) measurements, it looks like the tweak is saving £9 and 25kg CO₂ per year.  So yes, it's a saving, but it's hardly gonna prevent catastrophic climate change on its own (an average person in the UK produces 10,000 kg CO₂ per year and total human activities produce 27,000,000,000,000 kg of CO₂ per year).

(update: a good friend has pointed out that the numbers sound a little suspect.  So I'll keep monitoring the HTPC for a week or two to get a more representative sample)