Internet Explorer users may get a message "Authenticode signature not found" for run from present location. If so, just ignore it. It's a system administered by Verisign which is intended to help users to decide whether the installer is in its original state or has been virus infected, or is otherwise malignant.
Unfortunately the expenses involved for each program you sell are really high for a small busiiness, so only the larger software companies get these signatures. My programs are thoroughly virus checked using the latest virus definitions and Norton Anti Virus, and I assure you that they also have no hidden spy ware or trojans or other such things in them :-).
Lets hope someone comes up with a system better suited for shareware writers - the idea behind it is fine if the costs weren't so very high for what you get. With the low level of sales you generally get for each shareware program you sell, a fair number of shareware authors would earn nothing at all from their work if they bought these signatures, indeed they might well find themselves out of pocket to Verisign!.