Thank you all guys, just one question, what do you think is better:
1 - allow player to run (with stamina of course), do not mind the weapon weigh.
2 - do not allow player to run, make the speed of his movement depends on the weapon weigh (like in Call of Duty 2).
Which one is better guys?

choice #1:

i think it's better.
good luck again

I'd use a combination: Allow sprinting with stamina, but make the maximum speed depend on the weapon weight.

yep, seconded.

that's good too,but i think in ACION games the player should be fast enough,regardless how many weapons he/she had,some people hates "a bit reality mimic" and iam one of them
in games like 'IGI 2' you can't carry more than ONE primary weapon or even secondary!!!
i mean the game should be either "reality simulation" such as 'Operation Flashpoint' game or "fast action game" such as 'quake 4',

we have to mix it up, else the industry gets repetitive

Weapon weight doesnt slow down people running, but it does drain their stamina IMHO, so I vote for "allow players to run, but their stamina drained faster with heavier weapons"

even though true, thats not what players expect, in our minds we THINK we'd move slower, most players expect that

So I better make his speed slow depending on the weapons, but in the same time, players is allowed to run and his stamina must be lower down also depending on the weapon, am I right?

yes you are