I guess live chess does simulate OTB play, not exactly but I guess it is simulated...
This link has the rules of what you can and can't use as well as a list of caught cheaters. Basically you can use any resources you want in the turn-base game as long as they don't deal with your specific game, current position, past positions, future variations etc. So chess engines (like chessmaster) giving you moves, hints, evaluations, etc aren't allowed. Asking other players about your game isn't allowed. Looking up table bases in the endgame isn't allowed, etc.
Books, online articles, databases (opening explorers), are allowed. You can research the _type_ of position or specific opening all you want -- other than that though all your specific moves and evaluations have to come from yourself.
Some players do try to use engines. This site checks games for this kind of abuse and bans cheaters all the time (as linked above). The place do discuss cheating on this site is at the cheating forum.
I was a big fan of Live Chess (not my first account) on Chess.com (it simulates OTB, doesen't it?). I always wondered why aren't tournaments held on the LIVE setting.
So, I've tried Online.. and Dang, it's good..
Not as much stress and when you just want to leave the board - you leave it!
Altough it doesen't provide help with time-stress situations (like Live does).
.. I also have a question:
Is it considered cheating when a person is playing with the help of the engine? I personally don't (i want to get better, that's why I'm on Chess.com IN THE FIRST PLACE), but is it common?
Becouse, if i want to play VS ChessMaster, I can do it without going online..