All of the above is great advice...IF you are on a budget, you can also scan thenewx.org For Sale forum for used Off Road/Pro-4X stock skid plates.
However, if you plan to do any serious off roading (and if you bent a stock skid plate already...you're there), this is something to upgrade ASAP.
Gents, correct me if I'm wrong here, but order of upgrade/install would be:
-engine
-transmission
-transfer case (besides your rear diff, the lowest contact point for rocks)
-radiator
-gas tank
-rear diff
A lot of people will install the gas tank skid last - but consider this - the stock replacement cost, just for the part, for an Xterra plastic gas tank is in the neighborhood of $1,200...while the skid plate will set you back about $200.
A full set of skids from the two manufacturers listed by Toro should set you back (with hardware, meaning nuts and bolts to mount all) between $750 and $1,000...still less than the replacement of your gas tank...the last thing you should protect.
Just a few more thoughts to clog your mod friendly brain...