I will need to use a coupler to connect 2 cables, to make the xbox 360 cables reach my projector, which is ceiling mounted.

such as this...
http://www.monoprice.com/products/product.asp?c_id=104&cp_id=10401&cs_id=1040107&p_id=3002&seq=1&format=2&style=


Anyone noticed any problems with that, or should i run the cables through my receiver and than to the projector,

problem with using the receiver is that it will cost my an extra 20bucks in cables, plus it would be an overall longer run

Should work fine. The less jumps the better, so avoid the receiver connection - doesn't sound like there is any advantage in going that route.

For the roughly $6 + shipping in couplers, it's definitely worth trying it - should be fine.