MC won't run as a true Service. It runs as the currently logged in user, and can't run before any user has logged into the computer. So, if you want to do this so that it'll run even when NO user has logged into the computer, and it is sitting at the login prompt in Windows, then you're out of luck.
There are weird hacks you can do on Windows to turn applications into services, but this is not supported in MC, and if you do it, you're on your own.
HOWEVER...
If you have the computer set to Auto-Logon when it boots up, so it goes to the Desktop automatically (or the Start Screen in Windows 8 if you didn't upgrade to 8.1 for some reason), then you can absolutely do this.
In other words, if you just want it to auto-launch the same way other regular programs can auto-launch when you boot up (like iTunes for example), then yes, MC has this.
Tools > Options > Startup > Windows Startup > Run on Windows Startup.
Either of the choices there that include Media Server will automatically start up when Windows loads and logs in. The Media Server only mode will launch MC minimized to the system Tray, in Library Server mode (a minimal mode that just serves the Library). The Media Center and Media Server mode will do this, and will launch MC itself (the full UI).
You probably want the former from your description.
When you choose either of these two options, you can run MC "proper" on the computer and when you "close" it (with the X or whatever), it'll go back into that minimal Library Server only mode. To truly close it, you have to right click on the Library Server icon in your system tray and pick Exit.