Unfortunatly when this particular thread was created (2006) the forum software was a pre-dated version of vbulletin, and thus once the site owners upgraded to the newer version of Vbulletin stuff like attachements were not converted over.
Simply because the forum's code had so many adjustments made to it like custom hacks etc it was not possible to convert everything over from a heavily modified vbulletin version 2.x.x to a vanilla install of vbulletin 3.x.x