Calloway County, Murray, KY example

If you look up the IP address, it is a cornfield

It runs on your server.

Be sure to enable Windows firewall, or whatever firewall is available on your OS of choice. Keep up to date with patches for your OS. Keep up to date with patches for your browser, plugins (e.g. Flash), applications.

If you're running any internet-facing services (e.g. https) on your machine, keep those up to date & configure their security appropriately.

Install an AV package if you're really worried. Microsoft Security Essentials (MSE) is a great choice for Windows, because it's free, non-intrusive & not much of a performance hog.