Originally Posted by ddhytz 
Or download it now and keep it untouched for a few weeks. By that time any virus will become known to most anti-virus software and it will be detected.
I'm not SURE this actually helps, but I have downloaded exe and dll files straight to a CD and out them away until I was certain they were OK.
Of course the file has to pass through your processing system, so if it wants to offload some trojan or malware it will do so on the way through to the CD.