What Are The Best Weapons To Use On Rainbow Six Vegas On The Xbox 360 Multiplayer?

Of course, this depends on the type of mission or situation.  The weapons also rely quite heavily on rank, so I'll give my best answer given that some will be Elite and some will be Private when they play.

If you are starting out and you have access to the 92FS, it's basically a beretta pistol, use this, it's more precise, sturdy and although it's not the best pistol, nor automatic like the glock, you can still squeeze quickly and it has a large magazine.

The MP5N is a very accurate weapon, used by British police for accuracy and stability.  Put it on three shot and snap off short bursts.  This will help with hitting targets.  Stick a rifle scope on it and you can hit long range targets like a sniper. (well at reasonable distances).

If you can get a shield, it is the key to successive terrorist hunts completed and that's how you bring in the 600s per win (on LVU).