Jeeps are more effective chopper-killers, because their machineguns track with greater speed than those bolted to armour. Needless to say though, they're enormously vulnerable to rocket fire, as well as infantry weapons, so you have to stay on the move.
For pure comedy, you can actually shoot a Huey down with a shell from the tank's main gun. It's immensely difficult, but if you've a chopper coming straight down at you and your sights are lined up nicely, it can be done, and you'll click your heels and jump for joy when you achieve it... Although your squad-mates may not share your time-wasting mirth.
Aside from T-57 Russian tanks, the North Vietnamese Army has access to small trucks and tuk-tuks to get its forces mobile. There's something comically thrilling about barrelling into a US base or victory point in a tuk-tuk and stealing a freshly-spawned chopper or, even better, killing the pilot of one grounded for repairs and hijacking it.
Vehicle access is restricted by map choice, however. Phu-Bai Valley is the only map truly dominated by vehicles, as it spawns Bell Hueys alongside tanks, jeeps, trucks and tuk-tuks. Hill 137 and Cao San Temple are coastal maps which offer a little strafing action from riverboats, but largely drive both teams into brutal, infantry-heavy chokepoints.
Vantage Point offers a tank spawn to both sides, but there's a single hill-road between enemy bases lined with bamboo huts, which makes those tanks immensely vulnerable to RPG-sporting engineers and recon units with det-packs. Overall, vehicle usage is pretty well balanced against infantry strength.
As with Bad Company 2, objective-based games offer a meatier and more focused alternative to team deathmatch. Rush requires the attacking team to advance and destroy a series of key enemy installations, which soon become hotly contested flashpoints. Conquest is probably the favourite, with its series of re-capturable victory points, and capture the flag speaks for itself.
A cautionary note to PC users, however: you may have some difficulty getting the game to work at all. Initially the client wouldn't even connect to EA Online to let me browse servers, and after some trial and error I had to disable some on-by-default Windows 7 settings, set up a static IP address and monkey around with port-forwarding. Not what you really want when you buy a new game, particularly one that relies solely on internet play.
I must stress that not everyone has had such issues though. It all seems to depend on your particular setup, your router, and possibly your ISP's protocols. Xbox 360 and PS3 players needn't worry about such things, and the upside of the PC version, as ever, is the lovely visuals. Just be warned, you may need to tinker.
Like its forbear, Battlefield: Bad Company 2 - Vietnam offers yet more reasons to look beyond Call of Duty multiplayer and give something else a crack. There's a slickness to the combat, an intelligence to the map design, and a sense of atmosphere worth exploring, all wrapped up in a fast, fun, progressive experience that drip-feeds you goodies as you go. If you play Battlefield: Bad Company 2 multiplayer, it's well worth a tenner of your money. More of this, please.