Dashboard appearance

I have moved from 1.2.2 to 1.5 with the help of WordPress support. I have one problem left. At the top of the dashboard I see ‘WordPress’ and ‘Blogging in Paris’ (the name of my blog) overlapping. Of course, I realize I am the only person that it bothers 😉 but I would like to fix it. Which file do I have to modify, not forgetting that I am hopeless at php, no geek and know very little on the whole!