Just In Time Debugging Question/Microsoft Visual Studio Question HELP URGENT!!!?

Ok, I was running a program named RealPlayer and a message about Just In Time Debugging came up. I went in Microsoft Visual Studio and disabled JIT Debugging. RealPlayer started working perfectly then. Will my computer ever need JIT Debugging or not run correctly without it??? If so, can someone please tell me how to access visual Studio??? i know how to enable JIT so I'm good there. And on a last note, what is JIT Debugger and Visual Studio actually used for??? I really need to know and I appreciate the help. I will choose the best answer, which means 10 points!!!