A) Give it to me ... I'll have it if you don't want it.
B) Try out other Windows OS's with it, ones you haven't used before.
C) Try Linux out on it (Yay!)
D) Take it apart, take a look inside and get used to what the inside of a computer looks like. Look at the parts, learn what they are, and learn what they do.
E) Blow it up. I will give you my help, since I seem to be an expert with explosives.