I need some help with our home computer. Last night I accessed something wrong and somehow a virus or worm has gotten into our home computer. We have McAfee anti-virus software that came with the newer computer but somehow I screwed it up. The computer is a Dell Inspiron 620 with Windows 7.0 loaded. What is happening is I am getting some sort of pop-up window that looks like it is from "Windows" but I think it is a fake. The pop-up window is named "Windows Pro Defence", notice defence is spelled with a "C" and not an "S". Anyway it keeps telling me that our computer is affected with a Trojan worm and some other stuff and that we are at extreme risk. When I hit the "clean up" button, it then asks me for my credit card info and that this is for an upgrade to our present security levels. I am greatly concerned that I have somehow compromised our system and that I somehow need to get this cleaned up. Not even sure if our McAfee anti-virus software has been disabled or not. Please let me know if you can help.