Thanks for responding.
If I only download one copy of PunBB, and then create multiple boards, let's say one for each of 10 cities with 20 categories under each city, wouldn't I end up with a extremely long page - Chicago Forum, 2o topic categories, New York, 20 categories ect.
I would love to do it this way if I could just have visitors click on Chicago and then see the different categories, then click New York ect.
Any thoughts?

Hi,
I'm new to the whole forum thing and to website development in general, so please speak to me like I am a novice.
I've built a site on Yahoo! using site builder (I know, everyone hates Yahoo! and a drag-and-drop program is amateur, but I'm a writer, not a programmer.  But, I am determined to do this).

Here's my question:  I'd like to add forums to my site.  I want one forum per city - Chicago, New York,
San Fran ect. - how do I do this?  I plan on adding about 20 categories to each forum i.e. housing, dining ect. 
Since there will be links to each board on my site's main page, it would be nice if someone in Chicago could also post to boards in other cities. 
Again, I'm a writer, not a programmer, and I don't have a lot of time to devote to this each day.  Am I in over-my-head?  Can anyone imagine a better way of achieving this.  Help!  Talk to me like I'm a child.
Thanks for your help