NEED HELP!! with dell desktop xp reinstall?!?!?

I am only able to surf the web through ares p2p i have a virus that will not let me open internet browser or when i go into my controls system and try to press system restore also wont work stupid virus pop up... i looked up on a few forums to press ctrl and f11 at same time when dell blue bar comes up but i dont get a blue bar i get a DELL screen with a grey bar that loads then goes black then load windows i have tried ctrl f11 doesnt work..?? but it gives me the option to to press f2 for bios or f12 for boot menu, i have gone into bio sand set boot to cd i have tried pressing f12 then boot from cd-rom nothing works just loads windows!!!!!!!!!!!!!!! IDK WHAT TO DO :S plz help i got no program in c drive that ghosts it nothing idk what to do?????