I got ya. You mean to make sure you have the parent ROM, right? I got it running sort of. I DLed a set of like 9 Raizing shmups and a set of Bios. Well even though the bios DL was called complete bios it was not complete. So MAME is only recognizing like 4 of those games, I am assuming it is because I do not have the needed bios for them. I also DLed Undercover Cops(my favorite BMU) and got it working but it is not like it plays well with a keyboard.
Also, I have my PC set up with my living room TV as a second monitor. For whatever reason when I open a game in MAME it opens on the second monitor. I set mame to run in a window so I could "pull it down" to my PC monitor but that is a pain in the ass and I can not do it if someone is watching TV. Very frustrating. I never had this much trouble when I used MAME a couple years ago.
Also I have been unable to get my joystick to work. I'll try to DL some recommended drivers for that though.