Net trojanhunter updating
Should be updated regularly so it is able to detect and remove the latest spyware items.
Which email client you use is up to you, it is mostly personal preference, although some clients do have more/different special features than others.
Normal antivirus programs are generally not very good at finding and removing trojan viruses, so separate tools have been developed specifically for trojan viruses.
A web browser a program which can be used to view and navigate through the internet (the program that you are using to view this right now is a browser).
Detects, identifies, and removes viruses on the computer.
Viruses, like spyware can be the cause of many different things from the internet not working, to many error messages, to the computer slowing down, to the computer not starting up at all.
Basically this will stop you from browsing the internet even though you are still connected.