OMG, i can't believe that i hear things like "Mac os can do pretty much the same as windows..." when windows is just attempting (badly) to copy what MAC OS offers for like 10 years.
Leopard beats all that windows has when it comes to desktop. Software integration is the key of Mac OS, all seems faded together as 1 software and not that horrible patchwork that windows looks like.
When it comes to customisation, you can go the way you want and are ABSOLUTELY not obliged to work the way the developper of MAC OS want. You can change pretty much all you want and that is, without installing 9951451 third party softwares. You can even disable the dock if you don't like it... To be honest, the evolution of XP to Vista and 7 is just an atempt to copy Leopard, but let's face it, when it comes to design, windows fails.
Sorry, but thisplace needs a bit of MAC love and i'm here to bring it