If you click on the button next to the pictures where it shows you the file types it will give you a list of other file types you can look up such as archives which has your exe zip iso ect and then there is an option to search all file types and just type software or the particular software you are looking for but be careful viruses are quite common with file sharing and mslagent is a bad one with WinMix although I can easily get rid of these and therefore I enjoy winmix very much make sure you keep a constant update and check on viruses.
Well.. you can't really search for software in WinMX.. If you change the file type, that just gives you compressed media.
Chances are if you download software through shareware because there is a fee to download from the software's website, what is going to happen is if you get the setup download from someone else it is going to install then its going to tell you to buy now or maybe give you a demo for a few days but it will recognize that your computer is not registered and will know you have not paid for it, so even if you go through the trouble of doing it that way chances are you will still have to pay for it unless someone has a code breaking version