Getting the right feel for your game is important, anything that draws the players into your story, and makes them forget they're sat round a table covered in Dorito's has to be good.
A proper soundtrack is a good start, but lets face it, not many battles are fought with Jimi Hendrix blaring over the battlefield, for those grunts who aren't in the thick of it, their soundtrack is radio chatter.
Tension can be ratcheted up as characters on a Long Range Patrol pick up radio transmissions from another nearby platoon in contact with the NVA. A quick search of youtube for "Vietnam War Ambush" turns up quite a few genuine recordings of combat from the war:
You can extract the audio track of a youtube video using this simple tool, then drop it onto the portable MP3 player of your choice and voila!
Next, we'll take a look at the music your GI's are going to be playing in their hooch.