I work with computers since 1995. I started with 8080-based computers and I've met MS-DOS, Win3.1, Win3.11, Win95, SCO Unix, OSF Unix, Ultrix, Solaris, DEC and Linux. I know something about that. I think I'm an hacker. However that term is often mis-understood these days. I like Linux. I started with Slackware, because I can endlessly poke around, try to get things working or break them the way I want. That is what makes a hacker.

I don't try to break into systems. Well I tried sometimes, usually just by running Crack on password file, usually on systems where I could legitimally get access if I really wanted to.
I don't monitor any vulnerability lists, nor do not attend any 'hacker sites', nor do I study exploits. Mostly because I don't have time and I'm lazy to search for them ;-)
On the other hand most software I get for my system I compile myslef. The exceptions are really big things such as Open Office, Mozilla or Kylix.

Beeing a hacker, essentially means to know a lot about the system. To know what it can do, and what it cannot. To know stuff that most people don't bother to understand or lookup in documentation. And most of all, make use of that knowledge when needed.