Apple is currently advertising the fact that their new computers have "More Powerful Graphics". What the BRAND NEW MACS are shipping with are Mobility 5670 or Mobility 5750. Neither of these are good enough to run XIV and that's the best that an iMac can give you. The best a MacBook Pro can offer is a GT330M, also crap.
The only way to get a decent GPU in a Mac is to go for a Mac Pro. You can get a 5870 in it, and it will set you back about three or four grand.
Software-wise, Macs are great. Hardware wise, not so much. They all use the same parts and for all of Apple's great software innovations and hardware innovations like the iPod, iPhone, iPad, etc, they're horribly behind the curve when it comes to Apple PCs. They're great if you just want a system for general use or general video work, but if you're trying to do high end gaming, they are not the system for you.
Motorcycles are nice. They can be very shiny and fun to drive and many people would never ride another vehicle. But when you have a family of 5, a Motorcycle will not accomplish what you are trying to do, no matter how much you try to force it to.
Pick the right tool for the right job. A Mac has its uses, but it is not the right tool for gaming.
EDIT: And honestly, if you really want "A Mac" so much, OS X only costs $129; go buy it and drop it into your Windows box. Or just get a GNOME variant of Linux like Ubuntu.
Edited, Aug 8th 2010 2:26pm by Mikhalia
Mikhalia: and FWIW, my posts are 95% helpful, informative, or funny.
Mikhalia: only 5% or less of my posts are utter crap.
Tyapex: 393 posts of utter crap...
Mikhalia: Sounds about right.