If it's any help these are the minimum requirements for your PC ...
Mach3 Minimum Recommended Requirements:
Requirements if using the parallel port for machine control:
•Desktop PC (Laptops are not supported) with at least one parallel port
•32-bit version of Windows 2000, Windows XP, Windows Vista, or Windows 7 (64-bit versions will not work)
•1Ghz CPU
•512MB RAM
•Non-integrated Video Card with 32MB RAM(Large G-code files, especially 3D files will require a video card with 512MB RAM or higher)
Requirements if using an external motion device for machine control:
•An appropriate external motion controller (options can be found on the Plugins page)
•Desktop or Laptop with Windows 2000, Windows XP, Windows Vista, Windows 7, or Windows 8
•1Ghz CPU
•512MB RAM
•Video Card with 32MB RAM(Large G-code files, especially 3D files will require a video card with 512MB RAM or higher)
Tweakie.