I don't want to desillusion anyone, but there is almost nothing you can do against these infections on a normal system these days. Regardless of which virus scanner you use, once the bugger is executed a scanner can only prevent further damage by finding and deleting / quarantining files when they are written on the HDD __after__ the infection process. How can they start in the first place? Many Virii / Trojans camouflage themselves by building variants while spreading. Usually these stealthy ones only get caught by AV programs because they try to download and install further malicious code, which has a more static code and is usually in the signature databases of AV software. But until then, half of the infection process has already happened.
Then there are nice little buggers that control the data streams the AV software reads and simulate a clean system - the AV software will happily report that everything is fine. Or, a bit on the strong side, permanently deactivate the AV software and prevent every other known AV software from being executed or installed.
I liked the one that installed as a (signed!!) hdd driver and ciphered it. Now that was a creative idea. Once you get rid of the malware, you also have gotten rid of all the data on the hdd. Bummer!
AV software __cannot__ completely disinfect a system. Usually it doctors around on a symptom anyhow. I wouldn't rely on any desinfection software, because most infections I have seen were cross infections of several types of malware that started as a single infection process. The only thing most AV software can do is to delete malicious files, but what use is that when the malware(s) resides in the windows/system32 folder? And/or gets installed fresh on each system boot? And/or is a signed driver? And/or in the boot sector? Hides malicious data from it? This is like Don Quixote fighting windmills.
IMO, the best shield against that stuff is the own behaviour (__where__ do I want to go today..., and think before clicking "OK"), nevertheless install an AV software on the system, and running the web browsers + e-mail client strictly in a sandboxed environment (i.e. like sandboxie).
Cheers,
Mark
PS: If malware infects the boot sector of a hdd or parts of your backuped data (which you most likely will restore) you'll have it again after re-installing / formatting.
