Freeware is free, and
shareware usually means "try, then buy." All of the software that is submitted to Apple from developers to be downloaded from Apple's site is screened by Apple. Links to software from third-parties are also screened by Apple before they are made available, as well, so the downloads from Apple should be considered "safe."
You should always install updates to your Apple software, especially Security Updates. Security Updates are released periodically, but they only help to protect you from known compromises. New threats appear regularly and Apple is very good about keeping up with them; however, no third-party can protect you from yourself, so you need to be cautious about your activities on the Internet, regardless of any Security Updates Apple makes available.
You will find more focused attention to questions about computer and Internet security if you post them in the
Using Mac OS X Tiger forum.
Good luck.
