[sblock=Charge + slow]
That's a bit debatable. Slowed changes your speed to 2. If you use a move action to move 2 squares, can't you use another move action to move 2 more? If so, then you should be able to charge as according to the charge rules, part of the charge is a move so if you move 2 with your move action, then on your standard action, you can charge, which has a movement portion of it. Therefore, you should be able ot move up to 4 squares.
Slowed
Your speed becomes 2. This speed applies to all your movement modes, but it does not apply to teleportation or to a pull, a push, or a slide. You can’t increase your speed above 2, and your speed doesn’t increase if it was lower than 2. If you’re slowed while moving, stop if you have already moved 2 or more squares.
You cannot benefit from bonuses to speed, although you can use powers and take actions, such as the run action, that allow you to move farther than your speed.
Charge
A creature uses the charge action when it wants to dash forward and launch an attack with a single action. Such an attack is sometimes referred to as a charge attack.
CHARGE A TARGET
Action: Standard action. When a creature takes this action, it chooses a target. Determine the distance between the creature and the target, even counting through squares of blocking terrain, and then follow these steps.
1. Move: The creature moves up to its speed toward the target. Each square of movement must bring the creature closer to the target, and the creature must end the move at least 2 squares away from its start-ing position.
2. Attack: The creature either makes a melee basic attack against the target or uses bull rush against it. The creature gains a +1 bonus to the attack roll.
3. No Further Actions: The creature can’t take any further actions during this turn, except free actions.
A creature’s turn usually ends after it charges. However, it can extend its turn by taking certain free actions, such as spending an action point (which grants the creature an extra action).[/sblock]