Actually, I was not surprised in the least when Dell announced that they're going to begin selling PCs pre-installed with Linux. After all, it was quite obvious that they had it coming: the selling of PCs without operating systems, squarely aimed at the open-source market. Then the consumer poll that they held a while ago showed Linux as a dramatically popular option.
Dell obviously isn't trying to set Windows against Linux, but is simply trying to expand their markets. With competitors close at their heels, Dell is forced to make smart marketing decisions to help stay in #2 spot.
However, as unsurprised as I am, I'm still skeptical of how this is going to work. Dell is going to have to hire a lot, and I mean a lot more technical support staff, because their lines are going to be flooded with support calls. For 2 reasons: clueless people who decided to buy a pre-installed Linux PC instead of one with Windows, and the other which is that Linux is way harder to maintain/use than Windows.
Sure, you Linux techies can flame me. I'm almost one myself. But there's simply no substitute for a unified operating system (as opposed to one that's been modded a thousand times, and there really is no standard), and Dell's support team is going to have one heck of a time trying to keep the calls under control.
So the bigger question is: will Dell be able to make profits from a PC that requires extra support staff? Dell's tried it before in the past, but it didn't turn out so well back then. Linux's growing population is what prompted Dell to do it again. Perhaps it will be better for them this time. At least that's what Dell is betting on.