sure is confusion in this thread.
Apple != Mac != OSX
Microsoft != PC != Windows
Apple is a company that makes Macs which natively run OSX.
Microsoft is a company that makes Windows, an operating system that runs on PCs.
Macs now days come with bootcamp, so you can load Windows or Linux or whatever on to them the day you buy them. If you think "Macs have great battery life" then buy a Mac, and put Fedora or whatever on it, they are not tied together.
Operating systems have nothing to do with the physical abilities of a computer.
Linux is not 'a good challenge'.
It is as easy, if not easier to install than windows, and just as easy if not easier to use. There is no unwritten rule that having Linux means you have to play with the kernal or whatever.
All operating systems now days are equally easy to install, and equally easy to use. Look at screenshots of W7, Ubuntu, and OSX. They look practically identical. Task bar, windows, menu buttons.
None are harder to use, or easier to use.
Some people cry that OSX or Linux have less programs available or whatever. Every Windows program has an OSX and Linux equivalent. A native OSX or Linux user will have no problem with finding programs, it comes easily to them, just like finding Windows programs comes easily to a Windows user.
So what is the difference? At the moment there are 'heavy' OSs, which encompasses W7 (40gb or something?), OSX and Ubuntu; but of course Linux has a lot of lighter distros, I have seen less than 100th of W7.
Oh, and file systems.
Open Indiana and Solaris can use ZFS, the most powerful and flexible file system (Seriously, you can turn your drives in to a giant Momentus).
OSX and W7 both run inferior older file systems...
Honestly, when it all boils down to it... I think W7 and OSX are both great for 99% of users, both are solid easy to use operating systems. Linux is just as solid and easy, but it has a lot more options available. And because they are open source they often absorb new technologies and philosophies quicker than the others. Does everyone need this? No. These features make it to W7 and OSX, but it takes some time.
I don't see Microsoft or Apple making something equivalent to Chrome OS any time soon.
Linux is also generally considered faster, more reliable, more flexible, and more powerful, but I don't have the numbers to back that up (10 fastest super computers in the world run Linux though, so I guess proof that it is flexible...)
By the way, this is no where near a fair battle. Windows and OSX are esentially just 1 OS over many generation, Linux has thousands upon thousands of builds (Linux truly is the vast minority).
Linux literally has a flavor for every occasion.
This is Choclate vs Vanilla vs EVERY OTHER POSSIBLE FLAVOUR x 1000.