I would not advise editing any UBB files with DreamWeaver. For those, you are better off using a text editor if you need to edit any of the scripts.
Regarding maintaining the remaind of the site, it depends on what languages are being used. If you are using ASP, PHP, or Java for the rest, you will probably want an IDE (Integrated Development Environment) for the language. If it is just HTML, I don't see why DreamWeaver wouldn't do the job, unless you have a tool you like better.
My Site is coded in PHP, so I use Zend Studio. My HTML is written by hand (except nested tables. I use FrontPage to do tables)