Hi Henrique -RJ.
Not any single antivirus solution will catch all malware or have all the definitions. That is why it is good to have some additional non-resident anti-virus solutions (one that protects against this vbs.psyme.239 virus is ClamWin Free Antivirus (see here:
http://lurker.clamav.net/message/20061103.151448.69c9d2dc.en.html)
You cannot have two resident av solutions on one machine because of conflicts, but you can have one resident av solution, like avast, together with online scanners (e.g. Bitdefender etc.) and non=resident, like ClamWin, DrWeb CureIt, stinger.exe, fprot for dos (with automatic updater, yes it is still around).
Then a lot of people have the classical anti-spyware solution on their computers: ad-aware, spybot s&d, and when the computer is malware free a protective program like SpywareBlaster, anti-trojan scanners like a-squared and ewido makes this complete. Additional in-browser security completes all: in Firefox, we have DrWeb's pre-link scanner, MacAfee SiteAdvisor, Stealther, NoScript, AdblockPlus + G. updater. Whit security like that and SafeXP set, so I do not surf with full admin's rights, not a lot can get in harm's way,
polonus