If you really care about the TDP and energy consumption and f you want to save the planet without joining PETA or a similar group, you might want to consider buying one of the new, soon to launch, Core i3 Sandy Bridge CPUs.
The new Core i3 2100T, where T stands for Power Optimised Lifestyle, with two cores and four thread support at 2.5GHz can work at only 35W TDP. Yes, we know that Power Optimised Lifestyle doesn’t have anything to do with T suffix letter, but not everything has to make sense, it's just marketing.
The 35W figure is a big deal. Bear in mind that we are talking about desktop processors where 35W is about as low as you can get. In the mobile segment they tend to go even lower with the TDP, but for desktops, all-in-ones and home theatre market systems, 35W is a great achievement.
This CPU has 3MB of cache, supports dual-channel DDR3 at 1066 or 1333MHz, has graphics that work at 650MHz and hit 1100MHz on Turbo. It supports the LGA 1155 platform and new 6 series chipsets.
We can see some of these CPUs making threir way to AIO PCs, as you can get a lot of power that fits in this very compact form factor.