Suggestions for Modern Military "simulation" style shooters.

In September I am due to go to Marine Basic Training, and then spend at least 4 years Active in the USMC. I'm very excited, and one thing I've always been curious about is just how 'realistic' these types of games are. So I'd like to play through a couple of these games and compare that to my actual experience in the service. From what I've read about Arma II, the amount of physics simulation is pretty crazy, and I'd definitely like to give it a try. Any other games you might suggest? I would greatly prefer PC, but 360 is also an option. Somehow I doubt there are any games like this exclusive to the 360 that would be much better than a PC game, but who knows. Any suggestions would be great.

ARMA and the original Operation Flashpoint (graphically pretty dated nowadays, since it's over 10 years old) are the most realistic I've heard of. I don't think the later Operation Flashpoint titles strived for realism the same way though, but I haven't played them. Come to think of it, these are pretty much the only ones I've heard of. Sniper: Ghost Warrior was supposed to take a super realistic approach to sniping, but what I've heard, it failed miserably at it.

The ones game that I can think of that might be of interest to you is Full Spectrum Warrior (XB).  There is a command console in the XBox game that takes codes and one of the codes is SWEDISHARMY which is the most difficult mode in the game and takes away the HUD.

Overview:
Full Spectrum Warrior is based on a (failed) game commissioned by the U.S. Army to train light Infantry troops in urban combat situations. Soldiers are placed in a tense, hostile, and claustrophobic environment where they must complete a variety of military objectives. Players act as the Squad Leader, providing direction to Alpha and Bravo fire teams. The Squad leader does not shoot, but rather directs his teams to fire.  In some cases, a special team is added to add additional capabilities like snipers, etc.  The Army wanted something simplistic that could work on inexpensive hardware that could be provided in recreation centers, yet also teach good tactics.  Sadly, the Army version never really went anywhere because it was not realistic enough. 

I actually like FSW a lot, and I can tell you the SWEDISH ARMY mode is difficult.  In no way do I think it is as hard as Arma II, but you might find it enjoyable and it will play on XB and I BELIEVE it is backwards patched on XB360.    

Is the free Americas Army game still going? I mean, that's actually MADE BY the Army.

Close combat first to fight. I know no one listens to me say that, but this game really is authentic, uses marine tactics. Hell, i'm going to reinstall this game right now.

a bunch of tutorials of real marine tactics, you go find the rest if you care about it. 
http://www.youtube.com/watch?v=jpkBOSOcGXw&feature=related

" Is the free Americas Army game still going? I mean, that's actually MADE BY the Army. "

Make sure u get Arma2: Operation Arrowhead, nobody plays Arma 2 anymore. And you don't need the original to play OA.

ArmA II is probably the closest thing you can get to a realistic military simulator. There are plenty of military clans for that game as well. Go and check out the 7Cav, as they're the biggest ArmA II clan and I was formerly in that clan. There's plenty of ex-military personnel members in the clan so it can get pretty authentic at times.