I tried the demo for Arma 2 a while back and was put off by its performance requirements and overly complicated interface. Mostly the interface.

I'm okay with playing Arma 1 with its primitive graphics and all, but does it have the ridiculous number of commands and difficult interface that I associate with Arma 2? There were so many commands that some keys had to pull double duty and menus were often difficult to navigate.

Also, is Arma and Operation Flashpoint the same game? I'm so confused...

ArmA: Cold War Assault is the original (and awesome) Operation: Flashpoint.

I just found a manual for ArmA, and yep, the interface is just as complicated.

I suppose that there is a bit of a learning curve to these games.

Yes, there is definetly a steep learning curve if you're going in blind. But you can make it easier on yourself if you take it slow. Don't try to be a squad commander or pilot on your first try. Start out as a lowly grunt and get the hang of the movement and interface first. Then you can try additional dutys like commanding others.

That way you just need a handful of keys:

WASD moves as in every other shooter
the normal movement is at middle speed, holding shift lets you move slowly, double tapping W lets you sprint

Q / E let's you peek around corners and roll on the ground

Y / X / C changes your stance (standing / crouching / prone)

F changes your weapons firing mode (if possible) or selects your grenades (if you are carrying some)

left mouse fires your weapon (or throws a grenade if selected)

tapping right mouse brings up your ironsights or optics

holding right mouse holds your breath for a steadier aim
also, holding right mouse over an enemy spots him for the rest of the squad

with the mousewheel you bring up the context sensitive action menu
middle mouse selects an item on that list or activates the action icon in the middle of the screen (like entering a vehicle)

M lets you look at the map

B brings up your binoculars (if you have them)

K / O show your compass and watch

G shows your inventory

And that's all you need for your first few hours. Remember that sprinting gets you out of breath fast and worsens your aim until you recover. I would strongly suggest going online for further training. Many clans and communitys provide training sessions for newbies. So just ask around.