Basically, according to The Register, there aren’t enough Intel Atom processors to go around. And so while Asus has been producing an equal number of Linux and Windows machines, they haven’t been able to produce as many overall computers as planned. In other words, the reason you’re not seeing Linux models on the shelves is because they’re already sold out, leaving just the XP versions available.

This doesn’t seem particularly likely though, considering the fact that Asus predicted earlier this year that 60% of its Eee PC units would eventually be running Windows.

APC has a much more detailed article exploring the relationship between Linux and today’s low cost ultraportables. Asus, Acer, and other computer makers have definitely helped demonstrate that it’s possible to build a custom version of Linux that won’t scare away new Linux users. But when it comes time do something as simple as adding or removing software from an Eee PC, Windows users will find themselves in unfamiliar territory. Ultimately, the biggest accomplishment we may eventually be able to chalk up to Linux is that it gave laptop makers a bargaining chip and forced Microsoft to think about ways to extend the life of Windows XP and offer it for a low price to OEMs.

The APC Magazine doens’t offer any good explanation for why the Linux version of the Eee PC 901 is unavailable at the moment though.