Comparing exe files to Windows Service

Currently threader.exe is a compiled executable file.
However it could easily be converted to run as a Windows Service.

What are the advantages and disadvantages of each implementation?

Property	EXE	Windows Service
CPU usage	Can fire off multiple instances at once - let Windows work out the multi-tasking	Only a single instance
Security	Works with the same security privileges as the application calling it	Calls to SQL Server may not have privileges
Privileges	Cannot impersonate other logins	Can impersonate a system level user
Unattended running	Not possible unless other tools are implemented	Easily handled by the operating system looking after the service
Installation	Easy - just copy in the exe	Medium - requires installer
Updates	Easy - just overwrite the exe	Medium - Requires uninstall of existing service and the update
Terminating the instance	Requires Task Manager to kill	Can stop service from MMC