You are in an interesting position since you have a premier level certification (MCSD) but a less than premier degree. I think you would be better served by obtaining a Master's in CS/MIS rather than another bachelor's. However, I think you might be surprised at how well you can sell yourself if you can only get a foot in the door for an interview. Given your credentials and your experience, I think you can argue that your experience is equivalent to BA level knowledge in CS/MIS and see if it gets you anywhere. Only if you find yourself striking out completely should you consider going back to school.
This was first published in June 2001