My Gaming PC at home runs Windows 7 (we run iRacing Simulator on it). It's not that bad actually, I find it to be bulky as all Windows OS are. There's nothing to a MAC OS.
You can't run iRacing on a MAC machine so I bought a Gaming PC with- 8G RAM (16 MAX), 2-HDMI Ports, 3.2GHZ Dual Core A5 AMD Processor, Radeone 5670 Graphix Card and more.
I recorded my 13 year old son who's an iRacing guru at Charlotte with NASCAR cup car with 27" HDTV. I'm going to buy a gaming chair professional iRacing set up shortly and hook to the 55" Panny. He's the #44 car and wins. This is not a video game, driving simulator. This is a fixed set up meaning you cannot adjust the car, you must adapt to it. You'll notice in the video cars stepping out and spinning. Got to adapt, can't get on the throttle too early.