You know you are old when you realise that your best friend's wife (who is about to give birth) wasn't born when you saw Star Wars for the first time.
Also, you know you are old when you think that the music release 20 years ago was so much better than today's music (even if it actually wasn't).
Mind you I am also feeling old because I was looking up V on the Internet Movies Database (
http://uk.imdb.com/title/tt0085106/), and realised it was 21 years old. I remember being scared witless by that when I was 11.