Do you know the width and height? That would help out quite a bit. For example, a 40 inch wide by 30 inch high window probably wouldnt look good as a double hung unless you were able to increase the height by about 20 inches which would require some carpentry work.
She said 44" square, so I'd assume that means width and height at 44"... I missed it too on the first read
@ judy, I think that it would look fine either way, but probably a little bit more natural as a slider. A couple additional thoughts:
-44" is fairly wide for a double hung. I'd make sure that you get a high quality product, perhaps with sash reinforcement. There are only a few products out there that I would say reinforcement is NOT a big deal in that width.
-Sliders really don't cost much more in most window lines, so I'd be surprised if that comes out to be a big factor.