How should I setup (re., username vs real name) a classmates dot com type of forum?

[rnmcd]

What is your opinion on how I should set up the registration process?

Let's say that I have decided that users of this particular forum will need to show their real name.

1) Do you think I should have users register a login username (eg., Talisman) but have a required "real name" field in their profile that displays in their postbit?

OR

2) Should I have them use their real name as their login username?

Here are the problems I see with option 1:

• it feels like a privacy or security issue if you display both a username along with a real name.

Here are the problems I see with option 2:

• some users have the same real name and therefore, all of the John Smith's will have to alter their real name to make it unique.
• there might be a greater likelihood that users will forget that they need to login with their real name. I think people have a tendancy to use the same username on lots of sites that they are a member.