Your requirements can be met with Drupal out of the box and the best part is you do not need to pay for any add on modules for forum, SEF and theming is easier.
lots of people are saying use Drupal, but I can't find any decent magazine/news style templates/themes for it.
Drupal is the best, It is already useful right out of the box, but when you master and get past its the learning curve of it's architecture, you will be a webmaster god. I have noticed that all more or less visited drupal sites are sometimes slow. The next version 6.0 which is in beta1 now seems to overcome this issue. After that drupal will be the first among all paid and free competitors.
Learning Joomla is really pain in the ass. I'm still struggling to learn how to post! But I think - joomla is what i need for my site. I see a really good site running on joomla - http://www.itwire.com.au. About Drupal - I no comment.
it's not worth it, IMO. I don't know why so many people swear up and down about how great Joomla is, I really beg to differ. I appreciate the efforts they took to make the CMS, but it is way too bloated and laggy. There's a fine line between extensive and overly-complicated.
Well.. in that case.. you might want to use Joomla.. ifaik they lots of free template floating around.. drupal has less..but really i think flash is a more difficult thing to learn than CSS and HTML.
i am currently trying to build the same site in both Joomla and Drupal. I will let you now which was easier