does anyone know what the most powerfull weaponds are in fallout and how to get them
thanks:)

You might be better posting in the Fallout forum.
I did play Fallout and Fallout 2 some years back, though. Just play through the game and more powerful weapons will present themselves. As I recall there are rocket launchers, laser/plasma rifles and miniguns.

Thanks im only new to this site ,and new to fallout aswell and im finding the pistol and rifle not affective

If you are new to Fallout then yes, at the start of the game it will take you some time to get used to the combat system. Get an NPC to join you as soon as you can as that will help.
As for the site, just click on All forums and then you get a list of them all. Helpfully, all the games on the GOG site have their own forum, so you'll find Fallout in the list.

Slifer, there are not only powerful weapons, but also some nasty upgrades as well. You will love them...your enemies won't.
All in good time :)