well.. how long have you been using this computer? according to your description... you cpu and ram are VERY old.. pentium is a very old cpu... 1gb ram is not enough to run today's programs... i suggest that you might want to upgrade your ram... clean dust.. check for bad sectors.. BUT.. this is most important part.. I would like to know what browser you are using.. because as you know.. there are more and more features in browsers.. and it takes up lots or ram and cpu... if the slow process happens most when loading webpages.. you might want to try downgrading your browser or switch to more simple browsers such as google chrome...
