Timmy, this question of the dictionary definition of well-regulated is an interesting point, and one that needs more airtime:
From the 1700's meaning of "well regulated": "Of troops, properly disciplined."
See the following contexts from that period of time:
This quote from the Journals of the Continental Congress, 1774-1789 conveys the meaning of well regulated:
"Resolved , That this appointment be conferred on experienced and vigilant general officers, who are acquainted with whatever relates to the general economy, manoeuvres and discipline of a well regulated army."
--- Saturday, December 13, 1777.
1690 London Gazette No. 2568/3 "We hear likewise that the French are in a great Allarm in Dauphine and Bresse, not having at present 1500 Men of regulated Troops on that side."
"I am unacquainted with the extent of your works, and consequently ignorant of the number or men necessary to man them. If your present numbers should be insufficient for that purpose, I would then by all means advise your making up the deficiency out of the best regulated militia that can be got."
--- George Washington (The Writings of George Washington, pp. 503-4, (G.P. Putnam & Sons, pub.)(1889))
The above quote is clearly not a request for a militia with the best set of regulations, but rather the militia that is best equipped and trained/prepared.
The quoted passages support the idea that a well-regulated militia was synonymous with one that was thoroughly trained and disciplined, and as a result, well-functioning. That description fits most closely with the "to put in good order" definition supplied by the Random House dictionary. The Oxford dictionary's definition also appears to fit if one considers discipline in a military context to include or imply well-trained.
In short, when the constitution was written the phrase "well-regulated" was different than the common modern vernacular. Example after example from that time period shows that when "regulated" is used as an adjective, its meaning varies depending on the noun its modifying and of course the context. For example: regulated rifle (adjusted for accuracy), and regulated commerce (governed by regulations) express a different meaning for regulated. This is by no means unusual, just as the word, bear, conveys a different meaning depending on the word it modifies: bearing arms, bearing fruit, or bearing gifts.
See here:
http://www.guncite.com/gc2ndmea.html