slow computer!!! help please!

my computer is soo slow. like, even just pulling up internet explorer or msn, and even just paint, it loads slow, and it freezes up, and i can't do much at a time. i know it's not because of age, because this computer is fairly new. (two or three years). i do not have a virus, because i have avg and i've scanned it. my dad has said maybe it's spyware but i have a spyware agent. please help? any ideas, hints, anything? :4-dontkno