PC RequirementsMinimum
OS: Windows XP SP3, Windows Vista SP2, Windows 7 SP1, Windows 8
Processor: AMD Phenom II X2 555 3.2Ghz or Intel Pentium Core 2 Duo E8500 3.17Ghz
Memory: 2 GB RAM
Graphics: NVIDIA GeForce 9600GT, ATI RadeonHD 5870
Hard Drive: 8 GB available space
Sound Card: Compatible with DirectX 9.0c or higher
Network: Internet connection required for online play and product activation
Recommended
OS: Windows 7 SP1
Processor: Intel CoreTM i3 2100 3.10GHz or AMD A8 3870K 3.0GHz
Memory: 4 GB RAM
Graphics: NVIDIA GeForce GTX 465 or higher, ATI Radeon HD 6870 or higher
Hard Drive: 8 GB available space
Sound Card: Compatible with DirectX 9.0c or higher
Network: Internet connection required for online play and product Activation
The "product activation" part would probably indicate Steam. No one would use GFWL now and I'm not aware of anything that offers something similar. I guess they could be running their own servers and services, but I kind of doubt that if they can just offload all that to Valve without having the internet rip them a new one.