Here are the minimum requirements for running GameEx and other support docs. Pentium 3 800Mhz CPU (or equivalent) DirectX(DirectDraw) Compatible Video card, capable of 16 bit colour at 640X480. [Your video card does not normally need to be too special unless using videos or DVD, although older motherboard onboard video is not recommended] DirectSound Compatible Sound Card. 256MB Ram Windows 2000 (SP4), XP (SP2), MCE, Vista, Windows 7 250MB Free hard drive space Microsoft .net framework 2 service pack 1 Microsoft Direct X 9.0 Windows Media Player 9 or above If you are planning to run just MAME along with video snaps, marquees, etc. you would probably be OK at 250MB but that will not leave you much room for anything else. With the price of HDDs being very reasonable, a 1TB drive to store all ROMS, snaps, etc would probably be sufficient and allow you to use the 120MB just for your MAME executables and Windows.