[PvK]

Depending partly on how well patched, and largely on your firewall, a hacker with your IP address and the right tools could break into your computer, especially a Windows computer without a good firewall, and without the latest MS security patches. I don't think it's at all likely, though, unless you're inciting hackers. With a good firewall and latest patches, I think you'll blunt almost all script kiddie attacks.

PvK