Well usually if you blow up an image to such a freakin huge size, its gonna get blury and theres not much you can do about it. However you can try some Photoshop effects, such as Sharpen, or even try some of the artistics ones. Many of those effects will make the image that was blown up look much cleaner. Just mess around with some stuff, and experiment as much as you can, that's usually how I find the best stuff that I make is pure experimentation.
-Good Luck
-Luke