The zip file on its own isn't a problem as it isn't an executable so is no threat, what we don't know is are there any other elements that might unzip it into the temp location, causing avast to detect one of the unzipped files in the temp folder.
You might not have executed it or tried to unzip it, but something must have for the extracted file to be detected. So I can't give any assurance about if it could have been activated once received.
Based on the multiple on-line scans you have done I would hope that you are in the clear, especially if you have as suggested cleared your temp folder.
I would say that spybot and adaware are not as effective as some other anti-spyware applications.
If you haven't already got this software (freeware), download, install, update and periodically run it.
1. If using winXP
AVG anti-spyware (formerly Ewido) Resident scanner during trial On-Demand after trial ends. Or
SUPERantispyware On-Demand only in free version. Or
Spyware Terminator Resident scanner. Or
a-Squared free On-Demand only with free version(if using win98/ME).