Here's the deal with these: Auto tranny models only.
The 2005-2009 (2010?) models have an issue where the radiator will leak usually around 85K-95k. The leak allows radiator fluid into the tranny and will totally fry it costing you somewhere around $5000. There have been some legal issues about this, but there has never been a formal recall. Nissan has extended the warranty on these Gen 2 Xterra's to 80K, but as I mentioned it usually happens after 80K. Do a google for 'xterra radiator transmission problem' and you'll see.
Thankfully, there is an easy fix: Reroute the hoses to bypass the tranny cooler. Some guys put an aftermarket heater, but this is not mandatory. See here:
http://www.thenewx.org/forum/showthread.php?t=25955
The other main issue with the Gen 2 X's is that the rollers around the timing chain will wear prematurely causing a 'whine' and eventual major issues when the guides/rollers fail. Be aware of this before you buy. I believe there is also a 80K mile warranty on this issue as well.
I've got an '06 SE which is the spitting image of Typhoon's above (Night Armor I believe), except mine doesn't have the Duxbury beach sticker.
That's all I got, back to the fall run. It's on you know...