There's little question that Linux on laptops (and on PCs in general) is no longer nearly as complicated or painful as it used to be. The new problem is whether notebook manufacturers are going to readily offer Linux to consumers -- both regular folks on the street and corporate clients -- outside of designated niches.
That said, there is one rapidly emerging bright spot: the new class of "netbooks" -- low-cost notebook machines that use Linux as one of a number of cost-saving measures and which are designed to satisfy relatively undemanding computing needs. Still, even there the competition is fierce, and both the hardware makers and Linux development community will need to strive continuously to make a larger dent in the market.
Right now, Linux won't displace Windows in any significant percentage, at least in markets where Windows already rules the roost. That's part of what makes the netbook market such a fierce battleground: in Microsoft’s eyes (and in the eyes of many Linux users), Linux has a good chance of proving itself there as a prelude to making strides elsewhere.
But it will take more than just making Linux available to people as a hardware preload option to put it on even footing with Windows in the notebook world. The rest of the software in the Linux sphere has to also compete -- either that, or Web-based equivalents of applications routinely used in Windows will have to become preferable alternatives.
These things may be well beyond the ability of notebook makers to influence, but they’re worth keeping in mind.
Hardware And Driver Issues
Obviously there's nothing stopping someone from simply downloading an .ISO of a Linux distribution and installing it on any commodity notebook. Nothing, that is, apart from a) their inclination to do so and b) how well Linux runs there. The good news is that it's no longer a dicey proposition to install on a notebook any of the recent, major Linux distributions for desktops -- Red Hat/Fedora, Ubuntu, SUSE, PCLinuxOS, and so on.