It's not exactly a "you can't sue us" clause, but more like a "you agree to arbitration" clause. Courts will generally not construe such clauses to prevent suit in situations like if your XBox explodes and injures you, but thanks to the good old boys in Congress (fueled by conjured fears of frivolous litigation) and the laws they've passed endorsing arbitration rather than litigation, courts give more effect to such clauses than they otherwise would.