Suppose that my aunt is running Windows 7 and with permission, she wants me to access her hard drive through the internet and copy a file on her desktop. In this theoretical example, she is not a host or running server software of any kind. She is not running a browser, IM client, IRC client, or anything like that, but she is definitely connected to the internet. This example assumes I am not in a proximity where I can do any packet sniffing. Lastly, assume she has disabled all remote desktop software. Knowing her IP address, is it realistic to access her hard drive? Can I connect to her with a command prompt and access her files using telnet/DOS or anything like that? How would I go about connecting to get a command prompt and guess a password?

Type in the IP see if a router is listening on port 80 with an admin screen, then try the default password, then enable Telnet or whatever.