JW,
Yes, it is indeed an Enfield. The 3-band rifle you have shown was the "bread & butter" rifled musket of the Confederacy during the Civil war having only been surpassed by the U.S. Springfield as far as sheer numbers used on the battlefield. The Union purchased a lot of these while they were ramping up production of their own rifles. The South managed to import large numbers of them from England prior to and shortly after the war began until the Union blockades effectively stopped a lot of outside arms being brought in. After that, the South relied on captured arms to resupply their troops. I have an 1862 2-band that I have been told was a Naval contract rifle. It's a little shorter that the 3-band but otherwise looks exactly the same as yours. There are several dealers of Civil war weaponry in Gettysburg, Pa. that may be able to provide you with information and a ballpark figure of what the gun may be worth. You should be able to find who they are and contact numbers for them here on the net. Nice looking old piece to say the least, and it would be great if these old guns could talk. I'm sure they would have some interesting stories to tell!
BPS