How do I get rid of antimalware pop ups and other serious trojans and worms? My computer is being overtaken!?

For 3 days now, I have been getting pop ups from antimaleware....no matter how many times I uninstall it in my computer, it manags to appear again. It pops up about every 5 minutes on my browser, then I have another pop up in the left hand side saying remote attack from different IP adresses everytime. Along with ographic icons popping up on my desk top, although those are few and far between but still happening. Then another pop up saying registration required, with a list of all trojans and worms on my computer...as well as a pop up saying my internet explorer is infected with some sort or rook...Now, I have tried superantispyware....avg did absolutely nothing, and i have recently tried downloading free versions of windows live one care as well as kaspersky and i keep getting error messages saying that they can not be downloaded. What can I do to get rid of these viruses completely?????