An article by The Inquirer talks about the possible increase in the Apple share of PCs during 2006 due to the new Windows Vista.
Although critical to Apple, the article goes on saying that the main advantage of Apple is that they have now hardware that is basically the same of PCs, thus with the possibility of running PC programs with emulation. This will give users a new option between Macs and the new expensive machines that will be required to run Windows Vista. Apple may gain adoption because Windows Vista will also be expensive to upgrade.
In their own words:
A lot of people are going to realize they are going to hang onto their hardware for four to five years, so they might be willing to shell out a little more cash up front and buy the better looking Mac-intelatosh. After all, the two boxes use the same chips, cost about the same, and their operating system looks about the same. And, oh, by the way, the Mac-intelatosh can run Windows software in emulation. Of course, they'll be gobs of people who are sticking to pure WinTel, including the hardware builders and the extreme gamers, but they're a small percentage of the vast majority of home buyers.