Should I add columns to aspnet_Users?

Hello all,

I am using membership and roles which is working so far but the issue I have is where should I store other information about users?
Do I add columns to aspnet_Users, e.g. birthday, city, etc or do I use another table(s) and link to the aspnet_Users table - that would be my preferred choice.
If I use other tables, can I "piggyback" on the createUser call and run my own sql to add to the other tables for example: I create a user "foo" with password "bar" in the asp:createUserWizardStep control (username, email, password, confirm password) which creates a new row in aspnet_Users - can I run my custom code to create a new row in another table with the newly created UserId?

Thanks