i personally recommand SMF, the theme of it really cool.

I have never used IPB before. I've always used phpBB for the past three years on various forums. It's been great, and I've never had any trouble or propblems with it. Their arcade and chat box may not be the best, but you can always get a chat box from other sites such as www.mychatbox.com and copy the link code and put in into your forum. I've done that, and it works fine for my purpose. I presonally see no reason for having an "arcade" to entertain people with. It's a chat forums, so I treat it only as such. There are many Templates / Styles you can download from their site at http://www.phpbb.com/phpBB/catdb.php?db=2 or from www.phpbbhacks.com to choose from. Other mods are available to change the layout of your forums, but I've never used any for security reasons, and so it is easier to update my forums when new versions come out. I hope this helps. You can visit all my hosted forums at www.fightclub.trap17.com . Cheers, and peace!

I think phpbb is the best becasue you can chnage loads of settings compared to the other programs.

I currently working on a new website for my scouts group and i am planning on adding a forum on my website but i cant choose wich script to use . so can you please post your suggestions and if possible the reliability of the suggested script and wether or not they contain any bugs.

There are many poles on Trap17 which have compared various bulletin board software. Please refer them.

My opinion about all these new forums is that if all 6.4 billion people setup their own forum, what will be the usefulness of it? LIke these days, so many new forums are coming. These not only have fewer visitors but become frustrating for the host/admin. If atm is really interested in creating a scout forum. He must advertise it ewell or have some means to get members.
The forum scripts or software that he may use are
PunBB, PHBB2, SMF as in the order I prefer to install.

All of them are good. But I have recommendation to make depending on your requirements. If you want to add some games into your forums Simple machine forums and Invision Power Board will come first before others. But the problem with IPB is that the latest version is not always free whereas SMF is free.

But if you want just for the sake of forum I think phpBB is the best, it's free and easy to set up and modify around. But these days most of these forums can be integrated into content management sites which is even better, why not go for them and have more features in it?

Why not use the free version forum from InvisionFree Boards? It's free and it's one of the professional free forums. It's also hosted on their servers and you will not need to spend time installing yourself.

Simply sign up an account there and setup your forum configurations and you are good to go.
http://invisionfree.com/

I quite like that website, but if you want to merge your website with your forum, than doing the above might not be suitable.

phpBB is one of the best known free ones, but seems to have a lot of security holes in. I remember back sometime last year when you could make yourself an administrator simply by editing a cookie.

I've no experince of other free boards, but if you're willing to pay then go for Invison Power Board. You'll notice that the link in the quoted message above will install an invision power board, difference is that the purchased version is yours and it's a higher version and has more features.

I'm just looking at SMF now, and I'm pretty impressed with it! I might use it on my website, when it is back up and running