Still works if you take the ethernet cable off... (or modem if you get online wirelessly). You can use your pc but not go online without effort. Actually, just open up your pc and take the ethernet card out. Hand it over to a friend or neighbor and tell them not to give it back for however long you need to be off the net.Old skool way:
1.Unplug your computer
2. Cut the plug off
3. Now if you want to go online again you need to put the plug back on
Hmm, though this isn't much use if you want to get work done on your computer... Sorry...