Preorders for the PC version of Sonic Generations have begun on such digital distributors as BTGames, Steam, Direct2Drive, and GreenManGaming. Interestingly enough, GMG has posted system requirements for the game, while the others haven't.
While these system requirements are not confirmed, they seem genuine:
Microsoft Windows 7/Vista/XP Intel Pentium Dual-Core T4200 (2×2.0GHz) or AMD equivalent 2GB RAM (Windows 7/XP)/3GB RAM (Windows Vista) NVIDIA GeForce 8800 / ATI Radeon HD 2900 11 GB free hard drive space
Microsoft Windows 7 Intel Core i5 @ 2.66 GHz / AMD Phenom II X4 @ 3.0 GHz 3GB RAM NVIDIA GeForce GTX 460 / ATI Radeon HD 5850 11 GB free hard drive space
Sonic Generations will be released on PC, Xbox 360 and PlayStation 3 on November 4, 2011.