Not necessarily. Some people are silly enough to spend $1,500 doing just that.

Try 31 million.

Everyone who gets an RRoD or e74 within 3 years of purchasing their console gets it repaired for free.  Everyone who's 360 breaks out of warranty gets it sold on eBay or fixed using many methods such as the Hybrid X-Clamp modification.  I'd say less than 1/10,000 broken 360's just get thrown away.

Its not really a ridiuclous question, as soon as I read the title I also wondered how many are operable. Microsoft couldn't have repaired every single unit that got sent back to them

Why not?  Every consumer by warranty must receive a repaired console or replacement.  Every console sent back to MS would have to be replaced one way or another by law.  If it means MS sends back a brand new system, that does not count as a new sale so the 31.4 million figure is again still unaffected.

Ok so when I sent mine back, why did they send me a refurbed one? where did my origional one I sent go to? Im not making out thats theres a mountainous pile somewhere of 1 million unusable xbox's, but surly not all of them have been repaired

Presumably someone else got yours after they fixed it. Just like you got someone else's old box, right?

Could be why actually, mine might have had a problem that couldnt have been fixed within a resonable time, but it could be someone eleses refurbished later on, but I dont think every single unit has been repaired thats been sold, and that goes for  sony and nintendo as well

On purpose or not, this thread is flamebait and nothing more.

Just assume just about all of them because any broken one gets fixed.