If you wanna avoid having your game scratched, you gotta avoid moving (switching from vertical to horinzontal or vice versa) the 360 while there a game spinning inside.

About the first XBOX, the first gen. was the best model, since this was before they started using the Thomspon drive to cut down the cost price.
Also, sitting your XBOX directly on the floor if you have carpet will definilty reduce the life of you console.