Essentially, Steam will be a verification system for the retail version.

Steam will also have an offer to digitally download SR2 to a player's system if they don't want to leave the confines of their house. If you have a retail version, Steam is only going to verify that you have a real copy of the game when you are first installing and launching the game.

We're trying to use a very low impact DRM here, since we've seen some of the headaches faced by other major game releases in recent months. I hope that explains it a bit more clearly.

Minimum Requirements:
- Windows XP / Vista
- 2.0 GHz Dual-Core Processor (Intel Core 2 Duo or AMD Athlon X2)
- 1 GB Available System Memory
- 15 GB Available Hard Drive Space
- 128 MB 3D Video Card w/Shader Model 3.0 Support (Nvidia GeForce 7600 / ATI Radeon X1300)
- DirectX Compatible Display Capable of 640x480 16-bit Color Resolution
- DirectX 9.0c Compatible 16-bit Sound Card
- Broadband Connection for Internet Multiplayer

Recommended Requirements:
- Windows XP / Vista
- 3.2 GHz Dual-Core Processor (Intel Core 2 Duo or AMD Athlon X2)
- 2 GB Available System Memory
- 256 MB 3D Video Card with Shader Model 3.0 Support (Nvidia GeForce 8800 / ATI Radeon HD3850)
- DirectX Compatible Display Capable of 1024x768 in 32-bit Color
- DirectX 9.0c Compatible 16-bit Sound Card
- Recommended System Requirements Required for 2-12 Player Multiplayer or Co-Op

Remember to update your drivers now to avoid hassle later on.