Yes, you can add your customized title to the page by SharePoint Designer 2007.
Here are the detailed steps:
1. Open your site in SharePoint Designer 2007
2. Open the page you want to modify (e.g.: default.aspx) and change to Code View, navigate to the PlaceHolderPageTitle in the top of the page. And add your customer code in the tag.
Code Snippet
<asp:Content ContentPlaceHolderId="PlaceHolderPageTitle" runat="server">
<SharePoint:EncodedLiteral runat="server" text="<%$Resources:wss,multipages_homelink_text%>" EncodeMethod="HtmlEncode"/> -
<SharePoint:ProjectProperty Property="Title" runat="server"/>
</asp:Content>
3. If you want to add a customized title to all the pages, you can modify the default.master file in _catalogs\mastepage folder. Navigate to the Title tag in the Head tag, and add your customer code in the Title tag.
Code Snippet
<Title ID=onetidTitle><asp:ContentPlaceHolder id=PlaceHolderPageTitle runat="server"/></Title>
Let me know if you have any further questions.
-lambert