Delirious in Detroit writes in...
I have a law degree and an engineering degree, and I've been out of school for over 10 years. Will the engineering degree count against me in my application (particularly when it comes to grades)?
Law, engineering, and now writing. Man, my head his spinning.
I'd be shocked if your engineering grades hurt you. The implication in your question is that they are C's or the like? If that's the case, I'd mention something in the personal statement about the engineering degree and how rigorous that was. Though, you'll want to avoid saying something like, "I made it through engineering, so an MFA should be no problem."
Bottom line: Your transcripts, in most MFA cases, are mostly to show that you have a degree. If they love your writing sample, you're 90% of the way there, with your personal statement and letters of rec counting for most of the rest.