Thank you vosszaa!
I've been trying to figure out a problem like this since last night. Everytime I plugged my external back into my pc it was coming up as "no driver found" or something like that. So it was basically an unrecognized device. So in windows 7 I was unable to do anything with it...
I didn't know they made an MSU cart for the Genesis.... I knew about the SNES one and the library for that is rather large but the Genesis one has very few games