Remote Desktop App

Is anyone aware of a remote desktop app that allows me to control my PC while it is locked? For example, if someone walks into a room the computer would display the locked screen, but I would be able to use and access other features of the computer. I want to be able to leave my computer up at my office but locked so no one can tamper with my materials. Any app suggestions? I saw iTeleport, but I'm not sure if I can have that locked and still in use with my iPad. Any suggestions would be awesome!

Thanks!

LogMeIn might do the trick. I know the remote computer's screen is locked while in use. There's a free version available. Just Google LogMeIn for the link.