Its really hard to give a hard answer to your question.
Getting on the Internet is a lot like walking down the Vegas Strip.
You have to be careful.
Many of the "old standbys" like "download.com" and "FileHippo" have went over to the Dark Side.
They have "wrappers" on their downloaders. At times this can be avoided by, as mentioned earlier, by doing a CUSTOM install.
For the most part, always try to download directly from the "publisher". Example, you could download Firefox from a third party (Cnet ?) or directly from mozzila,org.