I found this :
1. In Firefox 2.0, go to Tools>Options.
2. The Options box is opened. Click Tabbed Browsing and select the User Interface Tab.
3. In the New Tab Button section, select Browser Homepage for the When load new tabs, load the: box.
4. Click Ok.
Not sure if that helps. Doesn't work for me.
If it doesn't, there's this add-on :
https://addons.mozilla.org/en-US/firefox/addon/777
1. In Firefox 2.0, go to Tools>Options.
2. The Options box is opened. Click Tabbed Browsing and select the User Interface Tab.
3. In the New Tab Button section, select Browser Homepage for the When load new tabs, load the: box.
4. Click Ok.
Not sure if that helps. Doesn't work for me.
If it doesn't, there's this add-on :
https://addons.mozilla.org/en-US/firefox/addon/777