Linux does have some competitive advantages that may encourage stores to sell it pre-installed. First, it is cheaper, so the store can advertise lower prices.

Linux does have some competitive advantages that may encourage stores to sell it pre-installed. First, it is cheaper, so the store can advertise lower prices. Second, many Linux distros look really nice, so if they have them set up on display their will be people who by it for that reason. Then, the first mover would get a reputation as the place that sells that awesome looking computer (and cheaper than the others). Third, their is little direct cost to trying. They can install it on a few laptops, then if it doesn't work, re-image windows on them. Of course, (I suspect) the main reason this has not happened yet is the (legitamite) fear that customers would be the computer and then say 'it doesn't work', when it cannot run software X, or open file Y.