Is there a way to get textboxes, labels and other wpf controls in xna that supports margins, etc that flexes for window size?
The official GUI systems FAQ thread in the XNA Forum: What GUI systems are there for the XNA framework?
CEGUI# is powerful, but it doesn't support the Xbox 360 (eg. its design doesn't include responding to game pad input) - a major overhaul would be required to refit it to be usable with something else than mouse and keyboard.