Be afraid, be very afraid of software you get via p-p. Even when good people are trying to share good software, there is often a problem (bad installer, etc).

If you absolutely must get a program via p-p, you may want to look into torrents. Find sources that have received at least a few positive comments from others who claim to have downloaded the file(s). Even then, no guarantee of safety. Scan everything before you open it. Wear a wetsuit.