Like a lot of people, I had high hopes for that one, but from the reviews I have read, it was released in a very unfinished form and is nigh on unplayable because of that. By almost every account I've read of it, the conclusion was: 'give it a miss'. Shame really, as we could do with a good chopper sim for 'Nam.
There have been a few, but none were that great, stuff like Medevac (the Search and Rescue revamp) and that other one that had a third person view of your chopper, the name of which escapes me at the moment (which was actually good fun, but hardly a sim, and that one doesn't run on XP).
If you get some of the Yankee Air Pirate missions for wings Over Vietnam, you can fly a Huey and a few other choppers in 'Nam, but the flight model is a bit bizarre, because they had to 'trick' the program into allowing rotary winged aircraft in the sim, so it's not that easy to fly the thing, even though the missions are actually good. You can see it in that 'Nam movie I posted a while back, and you can tell from the footage that I had to be a bit creative with the editing to make it look like it was under control!
You can fly a Huey in flight simulator, but you will be bereft of 'hot LZs' and guns.
Chock