Cool! That worked perfectly! I've been trying to play Metal Slug 3 for months now struggling with emulators. I heard about the Windows default emulator before but didn't realize how to run it. You guys should all try this because it will save you a lot of trouble with 3rd party emulators. Thanks Ninjavenom!
This is probably old news but a good way to unlock ROMS that are on your computer (Microsoft leaves them on for testing purposes - Metal Slug 3 is one of them which I'm sure you all know) is this:
1. Click Start, then click Run
2. Type Regedit and click OK
3. Right click and click 'Delete' on every folder under HKEY_LOCAL_MACHINE - this will change the ROM file status from hidden to accessible from Windows.
4. Reboot and enjoy!
this thread should replace that ISO sticky