Well, A report from the government of the United Kingdom discussing the benefits of open source software indicates that Linux could certainly alleviate this problem.
"A typical hardware refresh period for Microsoft Windows is 3-4 years. A major UK manufacturing organisation quotes its hardware refresh period for Linux systems as 6-8 years." A significant difference...a doubling even, of the lifetime of a computer.
Thus, a world using Linux would be a world with half the computer waste (and, admittedly, halved sales for Dell and the rest.)
A widespread switch to Linux could prevent millions of tons of waste from going into landfills. Every computer not needed would prevent the use of 240 kg of fossil fuels. Spread that out over the 17.5 million computers that wouldn't be going obsolete every year and Linux could deliver the world a much more sustainable future.
The good news is, the world looks like it's increasingly ready to upgrade from Windows. Most of Asia has switched, as least in part, to Open Source Software (OSS); some countries, such as Indonesia, also think that Linux changes scofflaws into legit users. Cuba has reported a 500 percent increase in Linuxswitch from Windows to Linux, and two out of three Dell customers are now demanding that installation in two years; of course, they can't really get Windows due to export restrictions. Big Blue is giving a specific tutorial to The Bird be pre-installed.
Many versions of Linux will run on a Pentium 1 with 128MB of RAM, while Slackware can run on a 486. It's also generally free, and available for download, so there's no packaging or shipping associated. Linux, it turns out, is far and away the most green way to run your home computer system. And, these days, it's as simple, as usable, and almost as pretty, as OSX or Vista anyhow.