In Dreamweaver do this:
Click on Edit then click on Find and replace, or use the Ctrl and F key shortcut.
You can select where in the web site to look from individual files, open documents, current document, selected text and so on.
You can also select to search within text, source code, advanced or a specific code tag, then you can choose further search options to help your updates.
FrontPage has a similar feature where you can select from various options for searching all pages or the current page. Your best bet is to stick with the manual find and replace, since when you find a snippet of code or text you can manually choose whether to replace it or not, rather than leaving the automated find and replace to run riot through your entire site. Only use the automated find and replace if you are 100% certain that all instances of your search are to be overwitten.
If the change is widespread you might consider making a template page for your site. All pages created from the template will be automatically updated with any new information when you change and save the template. I often use templates for sections of a site, so that I can alter one section, say, a few pages that list the services I offer. I can update the template page, change one link and all pages linked to the template are changed in one fell swoop. If you want to control your site it makes sense to divide it into small chunks in subfolders and keep a template for each site area. This allows you to update one portion of your site while leaving the rest alone.