I am in a similar situation, depends on your design  rules. I was able to
create a new site  with the aid of Frontpage 2003. Basically I cloned an
existing intra-gov't look and feel site and then republished the template up
to SharePoint. Then you need to create editable zones so that you can put
web parts on it.

Now if your design guidelines  get into the look and feel of how the web
parts look/work then you have a bit more work in customizing the web  parts
to meet your environment.

It is very possible to create a highly customized SharePoint site but
requires some design and possibly coding effort.