Poor gaming platform or poor drivers?

Okay sure this has been discussed but wanting some feedback. I have an Intel imac 20" 2.16Ghz w/3GB ram and x1600 video. Now I have a PC with an x1600 card in it so was expecting similar frame rates and detail levels in games on my imac as I am accustomed to on my PC.

But what I found was that performance of OpenGL games under OS-X (Tiger and Leopard) was surprisingly poor. So then I went and grabbed Parallels and ran the same games under Windows XP via Parallels. Same crappy framerates. Okay, that makes sense as it's running under a VM so better than Rosetta, for example, but not as good as running under the native OS.

So finally, setup Boot Camp and ran the same games under XP there. WOW. Easily triple the frame rates and am able to run at much higher detail rates and resolutions to boot.

Sure some games developed for PCs and ported to OS-X likely won't run as well under OS-X. In this case I would expect a reasonable drop in performance, but not playable vs non-playable - on the same hardware?! Is it the drivers then? OpenGL stack? I can't believe Apple would load up crappy drivers *forcing* me to run games under Windows rather than OS-X, for games published for both platforms. Or, is it the developers who port the games, such as Aspyr? What gives?

OS X is not great for games, and neither is Parallels.

You need to run Windows on it's own, with Bootcamp, to get the things running at full speed.

Despite Windows being poor for a lot of things, it does have features that are way in advance of OS X, like Direct X.

The x1600 isn't a stellar card though and new games like Need For Speed Carbon run very well in OS X on newer hardware.

Seems reasonable, however I game on a Mac and consistently have higher framerates than my PC brethren with similar video cards.