Virus vs antivirus is main arms race of Internet. Hard truth is antiviruses are mostly losing. Even if you run background antivirus monitor, even if you have it daily updated… It can take from hours to days for latest malware threat to end up in database of specific antivirus product.
Running few antiviruses so they plug each other's holes is bad because they usually catfight, tearing Windows apart while at it. But there is decent option of checking file with multiply antiviruses online.
One of such services is VirusTotal.
There are few ways to get your file checked with it:
- upload directly on web-page
- send it by email (size limit of 10Mb)
- use provided tool to upload from Windows context menu
Power users have extra option of hashing file (md5/sha1/sha256), submitting that hash and getting scan results if file had already been uploaded previously. Only one missing is option to check file from http/ftp link.
There are numerous antivirus engines used including such known brands as Symantec, Kaspersky, ClamAV, etc.
VirusTotal is clearly not replacement for running local antivirus (that may miss latest stuff but still good protection from millions of older threats) but it is great way to check suspicious or freshly downloaded files.