Because 95% market share does not mean a better product. The PC/Mac situation is similar to the VHS/Betamax farce of old whereby the inferior medium extinguished its superior rival to everyone's cost. Not content with stealing Apple's ideas Gates then felt the need to nearly run them into the ground. I'm glad to say he hasn't succeeded.
There is a common misconception that Macs aren't supported by the bulk of software designers. While this is often true with specialist business software it is not in other fields, especially after Apple's immense popularity resurgence of late. It doesn't matter anyway as PC emulators can be used to run PC only software to virtually flawless effect.
I run Sierra/MyTrack quite happily on my iMac and use a PC laptop for IB's Trader Workstation, steal4free platform etc. and have no complaints. The Mac has a vastly superior architecture and OS (X) (it can boot up in OS9 or OS X btw so all my old applications still work) looks better and is a joy to use.
The day I bought a PC laptop (mainly for reasons of cost) was a sad one for me but I at least don't use it for much else apart from a trading platform. Windows XP is a hideous operating system IMHO, though this only becomes obvious after a few days using OS X.
Been clicking the Ok and cancel buttons on your screen shot but nothing is happening. I think your computer has crashed and frozen. My advice is to take it back and tell them it is not working.
Didnt know it would provoke such bias/unbias comment
I just dont have any problems with viruses/etc. Stevet is probably referring to an older mac chip set and cannot load OS X.
For the record OS X is a flavour of Unix and is robust/fast/superior and the Safari browser knocks MS IE into the ground. Expect an MS 'underground' release of something to try and slow it down a bit.