Server side scripts allow you to interface with a database and process choices on the server to provide dynamic pages for different users.
You would definately need that if you are going to be doing surveys and/or feedback forms.
This forum uses ColdFusion which is a server side scripting language. The forum would not be possible without this. Of course FuseTalk was not written in Dreamweaver UltraDev.
Basically if you want dynamic pages that change without having to manually edit the HTML for every change then you need server side scripting. Almost every page that you go to now is dymanic and utilizes a database. Well that is almost every commercial website such as
www.newegg.com,
www.ve3d.com,
www.anandtech.com.
All that happens is the person makes an entry in the database via a webpage(or form) and the entry will then appear where ever it is supposed to.
I suggest you read up on your platform of choice.....
PHP=can be used on pretty much any server.
ASP=only going to work well on MS OS machines(I have no idea if someone has ported it to work under Linux).
ColdFusion=works on linux and windows.
JSP=any OS.
If you aren't a Linux guy then I would look at ASP.net. It is the updated version of ASP. The main problem is that UltraDev doesn't support it natively. I just think that it would be a waste to learn ASP if you aren't learning ASP.net because that is learning an outdated language.
Personally, I would pick either PHP or ASP.net which aren't supported by UltraDev natively. PHP can be added with a free third party extension to UltraDev. I have never been a fan of ColdFusion or JSP.
Feel free to PM if you have any other questions.....