You download Firefox 4 and type a search query into the awesomebar and it uses a search engine that you don't like.
I'm currently working on a job to upgrade a site built in Joomla 1.5 to Joomla 1.6. I have come across a lot of issues along the way and this will be a running blog post which will be updated when I solve certain problems. Joomla 1.5 to 1.6 template upgrade tutorial is a pretty good starting point. If anything is incorrect, let me know and i'll correct it.