If you opt for the Liberty, try to get one without painted bumpers. It'll look like crap REAL quick if you wheel a lot.

The Xterra has skid-plates, they do work somewhat, but not too well. You can get aftermarket ones fairly cheap though.

People will say the Liberty is better off-road, but quite honestly, I'm not sure. And my personal opinion may be slightly biased, since I confronted the same decision some 2 years ago, and it's obvious what I chose.

I just realized this has been covered recently