The current state of Linux is amazing. If we take a look at, for example, Ubuntu Linux, we have to admit that the Linux desktop is really becoming a nice, user-friendly environment. I'm truly starting to like what I see. I considered whiping Mac OS X from my macbook, but there are some reasons why I won't.
I like to mess around in Adobe Photoshop now and then. There is no serious Linux alternative.
I've got an iPhone, so now i'm 'stuck' with iTunes. I really like my iPhone btw.
I really like iPhoto, it is very easy to use and archive my photo's.
My entire music collection is in iTunes -> especially the song ratings are important.
Maybe those reasons can be overcome. But for day-to-day usage, I still prefer Mac OS X above Linux. Especially software like iPhoto makes life so much easier. The hardware comes at a premium but I think it is worth it.