03-11-2010, 10:15 PM
No, you did not read correctly.
The iMac tech specs page
clearly says that that **MAXIMUM** continuous power is 241W for the 21.5 version.
Nearly all of this is of course due to the screen. The 24" Cinema Display, for example, uses 212W as max. continuous power.
So, if we were to imagine the iMac as two separate components and assume the 21.5" screen used 200W max continuous, that would mean the COMPUTER part would use a maximum of 41W. And again, *maximum* means exactly that -- in routine use it would use less power than that.
This is probably why the iMac -- alone among all-in-one computers of this size, as far as I can tell -- is EnergyStar rated.
If your 4.5-year-old PC is hooked up to a CRT monitor (as would be appropriate for its age), then you can rest assured you are using WAY WAY more power to run the monitor there than any LCD monitor made by anyone. If you have an LCD monitor on it, you're still using more power than the iMac's LED-backlit screen at the same size and resolution.
Here's more information on this if you're interested.
Greenpeace themselves acknowledge that Apple has taken the lead on making their product line as energy-efficient as it can be.