Pistol:
The Browning 9mm. Was the preferred sidearm of the British SAS for a number of years. It has a fairly large magazine capacity and excellent stopping power. An excellent secondary weapon in urban areas. The accuracy and power of the weapon will be a big improvement over the lame and largely useless doom pistol.

OICW
The OICW (Objective Individual Combat Weapon) is a new weapon being created by the US military to replace the outdated M16 rifle and its variants. The rifle will toggle between normal and explosive rounds. Shown below is the rifle firing on semi-auto mode.

OICW with explosive rounds
The OICW rifle, shown below, is firing on grenade mode.

H&K MP5
This weapon is used by all elite Special Forces / Hostage Recovery Units. It has exceptional stopping power and accuracy up to 200m. This weapon is extremely accurate and hard hitting at close distances, and in many levels this will be your standard weapon.

Hand Grenades / Flashbangs
Hand grenades are typically used in hostage rescue missions as part of a distractive entry. Grenades can be lobbed long distances, or dropped at the feet of an enemy. These weapons are extremely versatile, and are an extremely dangerous proximity weapon. They can be used in almost any scenario. Seen below, a grenade is about to be popped through a window.

Flamethrower
Not exactly standard military equipment, but then again, there's nothing like a flamethrower for taking out large groups of enemies. Shooting out a deadly stream of fire, this is a weapon that is extremely hard-hitting at close to medium distances.
Thanks go to Stephen Browning for drawing (and then modifying) the flamethrower graphics for us.

H&K PSG-1 Sniper's Rifle
The most expensive sniper's rifle in production, each rifle costs around $10,000 US dollars. Due to the cost, it is only used by the most elite special forces units. Another factor that limits its real world use is the relatively short 'reach' of the weapon (most military sniping weapons can be used at distances beyond 1000m; while the PSG is only effective at distances up to 600m Also, it throws spent cartridges a massive ten metres - meaning that a military sniper using a PSG -1 would most likely be compromised.
In the game, the PSG -1 will be able to take out almost ANY opponent with a single shot, however, the reload will be extremely slow, and ammo will be limited. Its primary use will be for assasination missions, or to clinically dispatch an enemy from a distance. A screenshot of the rifle is shown below.