Also great - though BattleField Vietnam is a old game for 4:3
aspect ratio you can edit the referring config files in wordpad.
So - if you have a 16:9 or 16:10 display go in the folder BattleFieldVietnam/
Mods/BFVietnam/Settings to find the VideoDefault named configuration text file.
In these change: Renderer.FieldOfView 1.25 for 16:9 and 1.15 for 16:10 displays!
Note that in game a few things are still stretched - like example the aimcross.
Now you may ask how to enable your desktop resolution after this - therefore
you need to have a player profile created in the game as usual in order.
Pay attention to have the resolution changed and not 640 x 480 - then find the profiles
settings folder and there edit the Video and VideoCustom called configuration texts.
After all your other video setting are optimized its useful to set them to read-only
in their properties to prevent them from switching back to the old resolutions.
May be required to remove Windows 7 security update KB3086255 on order to play!