I've driven my Buick through worse terrain than that.
That said, the Xterra (dumb name notwithstanding) is a fairly capable offroad vehicle. It won't fall apart after a lot of hard off-road driving like a lot of other SUV's (or a Buick) would. Sandman's gets credit for having a spade on the roofrack instead of some dumb yuppie thing like a kayak or something.
Oh, and roll your friggin windows down.
J_A_B