How do i get a program called spy dawn off my computer????

t was discguised as something else. i have tried going into add/remove programs and deleting cookies and temp internet files. i can't find it. i tried emailing the help desk for the company but it comes right back saying there is no such email addy. i know it's a fake site for spy ware or something like that. well i don't know but i think it is. can someone tell me how to get it out of my computer? it keeps makin me have pop-ups from internet explorer. i have fire fox and NEVER had anything from ie untill this thing.