While in the enthusiast world faster is almost always better, a very important issue with PCs, both new and old, is power. Whether it be due to the heat a machine generates or the amount of electricity it consumes to run, energy efficient computing is a critical issue for many, and some companies are pushing to make it a priority. CEO's are known for doing strange things, often for PR, and most recently Michael Dell came out to introduce a new line of gaming systems and components, laced with a bit of green:

In his keynote speech at the Consumer Electronics Show here Tuesday, Chairman Michael Dell introduced a number of new gaming systems and components--as well as a program to plant trees that will suck up the carbon dioxide indirectly generated by the fast Pcs.
While I doubt any gamer is going to sacrifice large amounts of performance in a game for the sake of lowered power consumption, most machines do spend a large quantity of time idling and wasted energy is a pretty big field to fix. On top of exotic cooling solutions and pricey components, planting trees a bit of a strange way to compensate for a power hungry PC.

As a company, Dell is one of the biggest PC recyclers, and has made a name for themselves as one of the few companies that will take outdated equipment back at no charge. Other areas in which they try to help is by offering servers with mobile components, such as 2.5" hard drives, a tactic that many people use to keep a desktop PC cooler. All that power savings do come at a significant dollar cost, though.