I had 2003, then upgraded to 2007 2 years ago, and have just upgraded to a new laptop with Vista (my old laptop was dropped by my daughter and completely ruined). After installing 2007 on Vista, it would not let me get past the Registration step (Finale hang right after I got the "registration is finished" (or something like that). I had changed the Compatibily mode but it did not help.
I decided to spend $99 to switch to Sibelius instead of spending $150 to upgrade to 2009. It's a special promotion from Sibelius for Finale user. I've always hated the Finale's user interface anyway, especially with not being able to drag note(s) to change its pitch.