You may have assumed from the title that this is a pro-Microsoft post. It's not, but I do have to acknowledge an aspect of my life that Microsoft has supported in a very savvy manner: Gaming. It's something that is really only recently happening to Apple's desktop platforms, and not really through significant efforts on Apple's part.
DirectX is my problem. It is a Microsoft proprietary development platform and only exists natively on Windows OS and the XBox (named of course for DirectX itself). It's a technology central to the majority of PC games and requires cumbersome emulation on other platforms. Though there have been a number of steps towards open development platforms such as Open GL, which has been around for a very long time but was waning until a resurgence in popularity in recent years, DirectX still dominates the gaming space, and steers the vast majority of titles published to be Windows only affairs.
There's change in the wind. Apple's support for graphical applications such as games is absolutely better than it has ever been but OS X can never support DirectX. The number of Mac-compatible titles is growing daily, especially in the small indie games market. We as gamers have to stand behind those small indie and large established developers such as Valve (and their Steam distribution platform) if we want this movement to build up momentum. If you're a Mac user and you care about gaming, it's companies like Valve, Bioware and Blizzard (World of Warcraft has always been Mac-native) who deserve to profit from your gaming budget. We have to make it comercially imperative for them to continue pursuing cross-platform compatibility.
In the meantime, gamer iMacs the world over will continue to bootcamp Windows. Pushing open development languages and platforms isn't just good for us Mac fans, it's good for the developers and publishers who benefit from reduced development costs. It's good for bedroom enthusiasts trying to make a profit from their hobby and it promotes innovation.