Autostart and Process Viewer gives you a control over applications which start with Windows, and shows which processes are running on your computer. But the most important thing is that this program helps you find out which processes and autostart entries are new. You can "accept" a process or a program starting with windows, and if a new ("unaccepted") item appears - the program tells you about it.
Why? Simply because most trojans and viruses put themselves to the autostart, and\or, must run as a process, all of this without your knowledge (unless you have this program installed:). Of course having a good anti-virus and anti-trojans software is a must, but the key problem is that a certain trojan\virus may not be detected by this programs yet (for example because a trojan is new, and the databases of anti-trojan programs are not yet aware of them)