start applying sooner than later.
I am not qualified to comment on what agency is looking for a computer degree - but it seems many are. However, I would advise that if you have 2+ years before you complete your masters degree that you start applying a minimum of 12 months prior to your graduation. Most federal hiring processes seem to take at least a year, if not more. I waiting until I was out of law school and had passed the bar before I put in my first federal application and I am just now getting hired. Note - I graduated in Dec. 2006.
Take the shotgun approach (apply to 3 or 4 agencies, you can always lateral later on down the road).
As a nation we adhere to the maxim: "The object is not to die for one's country, it's to make the other poor son of a [gun] die for his." - Gen. Patton