This may be a bit of a redundant theme on this website, but if you are looking to buy a computer and you are concerned about reducing waste and promoting conservation a great option is to look to the vast resources for used, recycled or refurbished machines.
Buying pre-owned machines does not necessarily mean sacrificing performance or reliability. Many machines made within the last three years have more than enough processing power to handle all basic tasks and then some. As for reliability, some sellers offer limited warranties or protection plans. Not to mention that with a little research you can get an awesome bargain on a powerhouse machine by buying a model that was top of the line just a few years ago.
Notebook computers, as opposed to desktop PC's, are an overall better choice when it comes to reducing waste and promoting a cleaner planet. Notebooks are obviously smaller than desktops, use far fewer components and less packaging. They use on average about half the power of a desktop, mostly with the processor only drawing about 30 to 35W or less, compared to about 65W or more for a desktop CPU. In addition, laptop processors are designed for long battery life, which means they are designed to be ultra efficient in terms of power management.
If you need to purchase a new machine there are many great green options available to you. The U.S. Environmental Protection Agency recently established a set of new standards, known as the Electronic Products Environmental Assessment Tool [EPEAT]. Computers with EPEAT certification are designated with either a Bronze, Silver or a Gold stamp, designating different Environmental Impact Levels. For more information on EPEAT certification visit the link below:
Lastly, before buying a computer, it's good to think about what you plan to do with your old one. If it still in working condition then you may want to donate it to a reputable reuse organization. Below is a great resource to find a Responsible Recycling program:
In addition some computer manufacturers offer recycling programs that you can use, often for free. Some will give you trade-in credit towards new purchases.
Below is a link to a pdf which details the recycling policies offered by popular computer manufacturers: