Answer:
There are a number of different places to get free software on a trial or permanent basis.
Download.com provide a variety of both whereas for business software it is advisable to try Iris' free 7 day trial basis.
If you are really interested in free software then you might want to check out Linux, which is a free operating system (like Windows or Mac). There are different flavors of Linux out there to try (kind of like how there's Windows XP, Windows Vista, Windows 7, etc.). The most popular Linux distribution right now is Ubuntu, which is what I use, but there are tons of others as well, like Linux Mint, Debian, Fedora and more. You can even try one of these without installing it on your hard drive to see if it's something you might want. The way to try it is simply to go to their website (Ubuntu for example) and download the version you want to get. Then all you have to do is follow the directions they give you and create a Live CD which you can boot from and restart your PC.
Once you have installed almost any Linux distribution, then you can officially get whatever software you want from their software repositories for free. There is something there for everyone, all you have to do is find it.