Hey Knowledge...Welcome to AR15.com.
In the first place, I would not reccomend the Oly Plinker to you, for a whole host of reasons(most of which will get me flamed right off of this board).
They are cheap, because they are made cheaply. I have seen them, and the workmanship is second to all, with the possible exception of Hesse. Cast lowers? Don't drop it...
They also do not chrome line their bores or chambers-which makes sense for an ultra match rifle, where you try to wring every once of accuracy out of your barel but for anything else, utility, combat, is just plain cheap.
Chrome lining will make your barrel last twice as long, and make cleaning much easier, while preventing rust or corrosion in the bore. There's a reason the military chrome lined those m16s, as well as the barrel of the M9-it's to keep it from getting f'ed up. For chrome, you need to go with either Rock River Arms(if the chrome lined barrels actually ever happen), or Bushmaster.
Also, you will be using A2 sights on an M16A2, not the A1 sights on a plinker. Plus, if it's anything like MY two Oly lowers(and apparently about half of everyone else's), the magazine well will be too tight. Oly Arms will respond to this accusation by saying that it's not a problem with THEIR perfect lowers, but rather that everyone's magazines are out of spec(I own 30, Colt, USGI and Thermold).
Uh huh...MY first AR15 was an Oly, and I would have saved myself so much trouble by going with manaufacturer that cared about making things like magwells and chambers in spec.
I reccomed that you save whatever you can and buy a quality AR15 the first time around. WolfAR15 got the specs right-the closest thing to your M16A2 will be a Bushmaster XM15e2s 20" AR15. If you don't have an FFL in your area to order one from you, you can order them direct from Bushmaster, to be sent to your FFL.
As my dad said, if you have any other questions ask here, or hit me with them.
Juggernaut