What is it?
Logitech Mouseware - em_exec.exe

What does it do?
em_exec.exe - This is nothing more than a tray application that gives you easier access to things that are in your control panel. I prefer to keep the clutter off of my system tray and rarely change mouse settings so I would disable this from your startup.

Virus Precautions:
You'll want to keep an eye on this google search for any known viruses. The normal location of em_exec.exe is in your Program FilesLOGITECHMOUSESYSTEMem_exec.exe At this time my search shows nothing that you need to worry about.