Originally Posted by Frodo

Ziycon if you are running apache on xp there should not be a problem make sure mod rewrite is enabled in apache. I test using xampp on my xp machine and have no problem testing mod rewrite.

David my first one (no.2) should work as expected and leave the url as mysite.com/forum/ the same as with any other rule it doesn't add index.php, not sure why you thought it would.

The 3rd does have that obvious disadvantage but without knowing his forum setup it may the easiest way so its good to have it as an option, lateral thinking as you say.

Saying that I think your solution is the best one and would be the recommended one by me too.