Best would be a Windows Service.
see :
Writing Windows Services - Made easy[
^]
Few basic tips related to Windows Service
Installation
Open Visual Studio Command Prompt(Start>All Programs > Vistal Studio 20xx > Visual Studio Tools > Visual Studio Command Prompt.
Type in the following at command prompt to install the service
installutil "C:\Folder1\Folder2\Yourservice.exe"
Uninstallation
Open Visual Studio Command Prompt(Start>All Programs > Vistal Studio 20xx > Visual Studio Tools > Visual Studio Command Prompt.
Type in the following at command prompt to uninstall the service.
installutil /u "C:\Folder1\Folder2\Yourservice.exe"
Start/stop Windows Service
Open Command Prompt(Start>Run type in cmd will launch Command Prompt).
Next
Start the Service
net start Yourservicename
Stop service
net stop Yourservicename