MS loses money on every Arcade sold without accessories. Therein lies the rub.
Not many Arcades are sold sans HDD, extra controller, WiFi... or something.
The Pro/"Neo Elite" is basically just an arcade bundled with a HDD (heck it doesn't even come with component cables anymore, let alone HDMI) -- so they are profitable.
As someone previously in the thread stated, the X360 makes money as a brand -- you have to say "Arcade with no accessories and few games" if you want to claim they lose money on a sold console.
Sony is the same -- they lose money on PS3s, but make up the loss with pretty much the first accessory (or game) sold. Profitable from the brand standpoint.
I believe Nintendo is the only console manufacturer to make money on the base console unit (if you exclude the PS2 from consideration), although perhaps that's no longer true (I bet it is though), since the $50 price cut.