Suspicious looking "win7-pc" connection in "Shared" -- Hacked?

I can see a "win7-pc" connection in Finder>Shared. It is marked by a funny icon of a TV-tube-like antiquated PC. Could this mean my Macbook has been hacked? I never shared my Macbook with any Windows machine. But I do have WinOnX installed with a couple of programmes, and one of them (called Keyword Optimizer or something like that) looked quite dodgy to me. If this is a hack, I cannot find a way to remove it... It's not findable anywhere else on the Mac. Many thanks for any ideas.