I want to use a font that is not part of the default fonts listed in Dreamweaver. These being Arial, sans-serif, Verdana, etc etc.

I want to use Hattenschweitter, which I can select by ADDING.

But is this a good idea ?? What are the implications, if any ?

Else I will use an image of the text i want, but want to avoid this for page size purposes.

Cheers, Simon.

if someone doesnt have that font installed on their pc it will default to 'times new roman' in their browser I do believe

Like the poster above said, it will only show up if the user has that font installed. You may want to use a font list with 'Hattenschweitter' first, so users with it will get the best experience. But make sure your other fonts still look okay.
ie:

font-family: Hattenschweitter, Arial, Verdana, sans-serif;

its best to use something common, like arial, tahoma, verdana, times new roman, etc. unless you use flash you can embedd the font.

Got it, thanks for the detail.

Simon.