Paul Graham, and many others, consider an MBA to be essentially worthless, as do I. I decided recently against bothering to get one; I also opted out of pursuing a PhD for the same reason--neither an MBA nor a PhD will make you better at any aspect of doing technical work or managing technical work.
People like Paul Graham who have actually started up several successful companies and hired lots of technical people in various roles from top to bottom seem to find MBAs to be overly academic and irrelevant--they got in the way rather than facilitated progress.
PhDs seem consistently to be reported as merely a (very painful) rite of initiation to pursue research work.
I have a BS in Computer Science from the United States Air Force Academy, but I have decided to review/solidify my EE training. My actual abilities already put me well beyond a MS or PhD in Computer Science, but I see no value in getting the piece of paper. An MBA does not provide value, according to those who would know (plus my own experience). Even a MS in EE seems relatively unappealing--I am set on getting a vocational "degree" instead because I want hands-on practical EE skill rather than merely academic knowledge. I grew up with EE, now I want to flesh it out to its fullest extent as a complement to my CS skills.
I suggest getting your MBA-related expertise by reading a handful of decent MBA textbooks--you can get the academics without all the hassle, at least enough to complement your CS degree and to serve your actual work-related needs.