There is quite a lot of really shortsighted comments in this discussion. There are a lot of variables out there in the world other than what happens in the privacy of your bedroom where you might take the option of not using Windows at all.
I use OSX at home, I don't use Windows at all, although I
installed it with Boot Camp and Parallels just to see how it worked and be able to give an informed opinion on them (something that seems severely missing from the threads of this kind latey in the forums).
There is a lot of people that don't have a choice when it comes to what to use. Some examples I can give you:
-Work: There is a lot of software from Work that has to be used in Windows, not because there are no Mac counterparts (most of the time there are) but because they are not 100% compatible with the Windows versions and thus are not useable in an office where files need to to be shared and worked on by several parties. These are a few examples I can gather *right now* just from looking a the program list I have to work with (I use Windows at work). Please refrain from telling me the alternatives to these programs on the Mac. There aren't any alternatives that provide all the functionality we need to use on these. For all of these Parallels (or Boot Camp, albeit less practical) would work:
Microsoft Visio
Microsoft Project
MiniTAB
MS Access
Microsoft Outlook
Proprietary legacy applications
-Home: Same happens at home. Saying that "if it's not on the mac it's not really worth it" is a very narrow view of what people out there want to use or need to use. The same as I mentioned above, there are no true alternatives to the ones I'm putting here.
A *GOOD* GPS program (instead of the current half-baked or ancient GPS applications out there and the hobbyist Open Source or Single-task applications for the mac). A good example here would be OziExplorer.
Games. Please don't insist on this. Not only have we got to admit there are more games (and good games too, the "If it's good it'll be ported" argument stopped holding its own years ago) for Windows but something has become clear with Boot Camp: Even games that work in mac and windows run faster in Windows, IN THE SAME HARDWARE (there is a reason for this, and that reason is DirectX vs. OpenGL. I like OpenGL better than DirectX but the latter doesn't sacrifice optimisation in lieu of compatibility like OpenGL does)
GOOD synchronisation with Windows Modbile: The things exists. Don't ignore them. People use them, some of them don't have an alternative. No alternative exists for mac that covers all that the windows version can do, not even Missing Sync or the others. Especially when coupled with programs like TomTom or OziExplorer.
One thing is true, though. For a LOT of people the last hurdle to get a mac has been demolished. If they have a couple of programs they can't live without they can now use their macs and still use their windows programs at full speed (really, both parallels and boot camp are fast, WICKED FAST). They can now get a mac, use these for their special applications and use MacOS for everything else. This means a hell of a group of new users coming to the mac, and these users probably will start demanding their apps to be available for the mac. This will create new opportunities for existing developers and for emerging developers (especially those that adhere to Apple's graphic guidelines, remember how Google Earth, desired as it was by mac users, was dissed until it got its interface to meet at least halfway the Macintosh looks).
Being able to run windows at normal speed (VPC was never more than a second-best option, and actually meant a sacrifice for switchers) opens a lot of doors to new users (and existing users will finally be able to do all those things they couldn't do and insisted didn't need to do, but in secrecy wanted to)