Virus Total is about as useful as a ouija board or poo generator.
Because VT uses heuristic scanning the results can be misleading and full of false positives.
To expose the lameness of this technique I packed Control Panel from Windows XP and uploaded it to Virus Total.
The results were as follows: Virus.Win32.Virut.q!IK, Suspicious File, Virus.Win32.Virut.q and Win32.Malware.gen#UPX (suspicious).
I know for a fact there's nothing wrong with this executable but sadly other people might take their results the wrong way.
If I recall correctly Piriform had some malware accusations in the past thanks to Virus Total including the author of "Unlocker" who got his website banned thanks to crappy heuristic scan results.
The bottom line with Virus Total is it can be useful but don't take the results at face value because it's not reliable enough.
If you get many hits then you should consider your sample as viral, however with 2 or 3 hits you should treat it with caution.
Virus total can be really useful when used in conjunction with other things.
It is usually used to scan one file that may be puzzling a malware fighter for instance, he can check if anyone else is flagging it as a nasty.
If you look for instance at the Malwarebytes forum in the Malware Hunters area, each suspect file is uploaded and checked before definitions are put out to detect it. Have a browse through.
If you get many hits then you should consider your sample as viral, however with 2 or 3 hits you should treat it with caution.
That's exactly how I determine the final results. Too many times only 2 or 3 hits is nothing more than a false positive and too often it's the same offending antivirus engines doing it.