Yes, those are good tools but you only need to wipe the quarantine folder and then the free-space, once in this case. You use multiple overwrites to block the forensic recovery of sensitive data.
A single overwrite will prevent any chance of a program running again, and with the size of today's hard drives is the way to go.
There again, if you are certain that your anti malware overwrites rather than just moves to quarantine or flags as deleted; you would only need to zap the quarantine folder. :)
Of course it would still be there technically, but in an overwritten state.