the manual tells that rangers can dual wield, but no matter what i have done..he keeps only using one sword at a time..can anyone enligthen me on this?

I don't know if I am exactly correct, but the Infinity engine will not support dual wielding. Instead Black Isle gave rangers and extra half attack per round over fighters, in effect 3/2 where a fighter would have 2/2. Also, if you could dual wield, you would only be allowed a sword and then short sword, knife, or dagger not two swords.

Does it mean you should put a sword and THEN a short sword in the first two sockets of the quick weapon sockets ? How are you sure to benefit from this extra attack ? My ranger seem to strike more often than my warrior but I'm not sure it's true

You cannot eqip 2 weapons, it's a limitation of the Infinity engine. What was done to make up for it was to give the ranger extra attacks when useing a one handed weapon, to simulate the effect of two weapons. Remember, this works only on one handed weapons and you must not have a shield, bow or anything equipped that would take up both hands. This includes having a bow, halberd, crossbow etc, equipped as your second weapon (like how you can't use a shield if you have a two handed weapon equipped) but there's this really cool scimitar available in the game that gives an extra attack per round, so combine that with the Ranger's natural double attack and then Haste him and you have a whirling blade of death!!

It says in the manual that rangers cannot use two weapons in this game. Instead they get an extra attack if they don't equip a shield. Cheers