cureit doesn't download any signatures. which means that you need to download the program itself anew to have it stay up-to-date. rockets, no, you do not have to uninstall your AV. cureit is a cleanup program, not a standard virus scanner. as to how you know a machine is 100% clean, you don't, unless you disconnect a 100% clean machine from the network -- you can use one of the online virus scanners to check it out though. then run cureit. afterwards, burn your AV to CD; that way it positively cannot be changed by a virus, or get a virus scanner that insists on a password for changes. keep the virus definition file scrupulously up-to-date; it should download signatures at the very least daily; safer is hourly. if your AV doesn't do that automatically, chuck it out and get a better one. if you find that your computer has been infected, and your AV cannot clean the virus off, don't panic. usually there is absolutely no need to reinstall your OS or reformat your drive or anything like that. plug the name of the virus into google and search for removal instructions. all the big AV sites have those. pick one where you can follow step-by-step. print it out.