While it still could be unbelievable for some, lately there has been an unusual demand for new machines running pre-installed Linux operating systems. So unusual that Wal-Mart couldn’t fulfill its orders for Everex’s $199 PC.

Until the last few months, buying a PC that was running Linux was a bit hard. Today, Linux is a wealthy and powerful alternative to pre-installed Microsoft’s operating systems. However, one cannot restrain from wondering what’s behind this growing interest towards open source, and I have no valid answer for you yet.

Drawing a line, last year, only 39% of new computers went on sale with Windows Vista pre-installed, compared to 67% for Windows XP in 2002 (a first year of full availability).

It’s not just consumers that are seeking alternatives to Windows. Last week, the British Educational Communications and Technology Agency advised schools in the United Kingdom not to upgrade their PCs to Vista, suggesting they instead eye lower-cost Linux systems the next time they need new computers.

With a host of new Linux PCs hitting the market this year, U.K. schools — and other buyers seeking computing alternatives — will have more options than ever should they decide to steer away from Microsoft.