Menu Writer 2 is not compatible with Dreamweaver 8. The system requirements for menu Writer 2 are:
Windows
* Windows Vista, Windows XP SP2, or Windows Server 2003
* 128 MB RAM (256 MB recommended)
* Dreamweaver CS4, Dreamweaver CS3
Macintosh
* 500 MHz Power PC G3 processor
* Mac PowerPC or Mac Intel
* MacOS 10.4.x, MacOS 10.5.x
* Dreamweaver CS4, Dreamweaver CS3
Requirements for a Database Driven CSS Menu
* PHP 4.2+
* MySQL 4 and MySQL 5 (with PHP)
you can find this information on the menu writer 2 support page:
css-menu-writer/