I use Flight Simulator X, acceleration, and i think its pretty great!
The helicopters you get with the game are not that thrilling, but if you take a look at some of the add-ons you can buy/download, then it gets interesting
Take a look at
Nemeth Designs
I use my four year old gaming machine, and as long as i keep the details at a reasonable level, it manages alright.
If you'd like to fly offshore, you can download oil platforms from
The ODG Project - Creating realistic offshore related scenery Worldwide !
The online part is nice as well, you choose a server and fly, if youre lucky you'll find a server with a decent ATC op, that just adds to the experience.
For controls i use the logitech G940 set with joystick, pedals and throttle, its excellent!
Happy flying!