Windows

Windows Vista/7
Intel/AMD dual core processor (quad core recommended)
OpenGL 2.1 compatible graphics card with 256MB
1280x720 display resolution
Windows compatible audio hardware
2 GB RAM
2 GB of free hard disk space (for temporary files)

Mac OS

Mac OS X 10.6 (Snow Leopard), 10.7 (Lion), or 10.8 (Mountain Lion)
Intel dual core processor (quad core recommended)
OpenGL 2.1 compatible graphics card with 256MB
1280x720 display resolution
CoreAudio compatible audio hardware
2 GB RAM
2 GB of free hard disk space (for temporary files)

Supported hardware (check About This Mac / More Info / System Report / Model Identifier):
iMac 7,1 (mid 2007) and later
Mac Pro 3,1 (early 2008) and later
MacBook 5,1 (early 2009) and later
MacBook Pro 3,1 (mid 2007) and later
MacBook Air 2,1 (late 2008) and later
Mac Mini 3,1 (early 2009) and later