I honestly haven't had the chance to play any of the Battlefield series of games; most likely because I'm such a fan-boy of the RtCW/ET series ;) However, I have heard that they are great games, & if you're into BF: Vietnam, you may want to check out this tweak guide the gang at TweakGuides (whodathunkit?) have put together.

"Due to many reader requests (and better late than never) TweakGuides.com has released its Battlefield Vietnam Tweak Guide. The guide contains descriptions of all the in-game settings, troubleshooting tips, and all known working tweaks designed to ensure that you can run BF:V at its best on your machine."