Thanks for the help Husar and sapi!.
I have another question concerning the graphics card: does how higher the number means its better?
Like a nVidia GeForce 7500 is better then a nVidia GeForce 7300?, because I have found a good system with a nVidia GeForce 7500 LE TurboCache 512 MB. This one should be alright compared to the MTW2 recommanded system requirements.
What's your opinion?