Surround is created horizontally not vertically. Ceiling speakers are better suited for pro-logic and other systems to spread music across a wide area.
You want in wall speakers... lots to pick from... decide what type of speakers you want (Price/timbre-soft or bright/size) and you'll get more feedback.
Derric...the mythos are phenominal speakers, they will work well with your NAD. I would not hesitate purchasing those. I don't like in wall speakers so I will defer comments to someone more knowledgable about this product. If you would like a small surround speaker, I know that Mythos line has a small surround speaker that is available. I can't remember the name of it specifically, I only recall reading about it in a Home Theater magazine. I am sure you could find info at their website