I'm afraid you can't have it both ways: either you opt for ease of use, or for security. It's up to you to assess your risk, given your home and its security. Adding theft impediments like security cables will thwart casual or hit & run theft, but may not deter the determined burglar who manages to get in when you're out. But the age of your Mac is a deterrent by itself, because the halfway knowledgeable thief will pass it by for greener pastures...
