Hello gdownsu.
You'll have to tell us a bit more - like how much Ram you have, which anti-virus, firewall etc you have installed and for how long this slow-down has been happening & are you receiving any messages. What kind of Internet connection do you have? Are you running a pc or laptop & which manufacturer.
There are lots of causes for a computer to run s-l-o-w including viruses, worms, trojans and simply not good enough hardware. Please tell us what your pc consists of..
Thanks
Oh dear, Flame beat me to it, but you see gdownsu more than one asks for much the same info.