I run FSX via bootcamp on my 2010 Mac Pro and get decent (to me) FPS, about 20-30 at sceneries like Dulles, Dubai, Miami, etc. I am using REX with FTX Global and Opus for Wx. In the VC on the ground I get mid to low 20s and at cruise get mid 30s and above. Definitely not stellar performance, but if you optimize your setup, you should be able to get some decent frames on the iMac. Before the Mac Pro, I had a 27" iMac (late 2009 I believe), with a 2.8Ghz Quad Core i7, 16GB of RAM and a ATI Radeon 4850 with 512MB. I had that when the NGX came out and I got ~25-30 fps on that with the scenery at the time (FSDT, etc). At least you get an Nvidia GPU, I'm stuck with the ATI and the Nvidia is a $550 upgrade It definitely should give you some reasonable performance.