How would you ... check attachments before allowing them to appear on your forum?

[twobob]

If we allow members to attach files to our forums, is there a risk that they could be uploading a malicous file that then spreads a virus or something if a visitor downloads it from the forum?

If so, how can we protect our forums against this? Would you have those threads sent to a Mod Review queue first, have the Moderator download it and check it, and if it's all ok then allow the post? If so, what environment would you use to check it (ie if the Moderator downloads it onto their computer, aren't they at risk of being infected)?

Or am I just being a little paranoid? Thanks for your views ... cheers, twobob