as emailing and WP need very little in the way of cpu power. you wouldnt see any real world difference. im guessing you already have an am2 2.0+ghz cpu? which will be plenty for what you want.
if you were doing video encoding then yes you would see a marked difference. but if your getting it thinking it will make your system noticeably faster on basics, like word processing then the chances are it wont by much.