Linux normally struggles with wireless because of a lack of drivers, caused partially by the failure of manufacturers to release specifications so that drivers can be written (perfectly within their rights though). OEM, which is where most laptops and embedded devices come from, solves that problem. An OEM is not going to ship a Linux system with wireless hardware that has poor or non-existent Linux drivers.
Laptops are the hottest commodity these days and finding Linux drivers for the hottest new notebooks often impossible.
So true, but as above, most OEMs aren't shipping those with Linux. In many cases it's up to the poor user to find drivers to make it work, or use the kludge of a wrapper around Windows drivers (NDISWrapper). The latter kind of blows it for the philosophical purists since they have to use proprietary software (oh no, the world's gonna end!).
If Dell put out their owb O/S they might find a few fringe buyers of Linux but not enough to offset any loss of collaboration with Microsoft.
As a consumer I hope their Linux sales take off if for no other reason than increased competition. If Microsoft drops the price for Home because of this then the consumers win again. If it fails, well, one more in a long list of PC industry casualties, which are fine with me as long as they didn't die because of anti-competitive behavior.