Easy Private Forums for Drupal

So, I'm trying to migrate a phpBB-based forum to Drupal, so that I have a "integrated" software that provides more than just forums (blogs, pages, etc). When I hit a road block: Drupal out-of-the-box has no equivalent of phpBB's "private" forums!

Luckily, if all you want is phpBB-like private forums, there is a fairly easy solution:
1) Install the "tac_lite" (Taxonomy Access Control Lite) module, from http://drupal.org/project/tac_lite.
2) Activate the module
3) Assuming you're logged in as administrator, go to Administer >> User Management >> Access Control >> Access Control by taxonomy. You may need to click "Access Control" first before the sub-menu shows up. Alterately, jump directly to it by going to http://your-site.com/admin/user/access/tac_lite.
4) On the settings tab, in the Vocabularies box, select Forums and then click "Save Configuration".
5) Now go to the "Role based privileges" tab, and you'll get a page showing each of the roles you've defined, and for each one, a list box containing all of your forums. Select the forums that each role should have access to, and you're done.

This approach will give you private forums by role. What it won't give you, is permissions (read/write) by forum: a given role has the same permissions (configured in the Forums module) for any forum it can see. So if you have a need for a user role to be able to have read-only for some forums and read/write for others, you'll need to try another method.

For further information about how to make parts of your site private, visit http://drupal.org/node/111576. Take it slow, that page is jargon-heavy and will quickly confuse you if you're not careful - but the information for how to create full-blown private forums does seem to be buried in there. If you're really a glutton for punishment, try reading http://drupal.org/node/37742 for a "newbie friendly" (their words, not mine) explanation of Drupal's taxonomy system. It's particularly unpleasant, but if you feel a sudden compelling need to bash your head against a wall, go for it.

Aside: it's not that I don't understand Drupal's taxonomy system. I've enough background in this area to understand what they're trying to do. It's a tough nut to crack. Drupal's implementation seems overly complex given the nature of the problem. At the very least, it desperately needs a simplified UI to hide the complexity for common use cases.

*edit*

While this approach will prevent users from seeing the content of the private forums, it will not prevent them from probing for the existence of the forum itself. For example, if your "top secret admin area" forum is forum 12, then a user can still manually enter /forum/12 and bring up part of your forum page (showing the name of the forum, possibly more) though they are prevented from seeing the details. Whether this is a bug in the forum module or the access control, I don't know. Just something to keep in mind when choosing forum names.