Use OWA as a forum

We would like to use a set of public folders in Exchange 2003 as a forum. Like this, there is no need to install special software and create links for authentication etc. All our students could (approx 500) use OWA to read their e-mail and can use OWA also to work in the forum.
Some modifications would be necessary however
– change the display of the folder by default by topic/converstation
– make the default reply the post in this folder and not via e-mail

Is there an easy way to do this?
If not, are there any good alternatives

Thanks
Pieter