This is what PT 2007 says when checking for updates:
"jv16 PowerTools 2008 has been released!
jv16 PowerTools 2008 is a free update for all customers who have purchased jv16 PowerTools 2007 after or on 1st of October 2007, your existing license will also work with jv16 PowerTools 2008. For customers who have purchased jv16 PowerTools before the 1st of October 2007 the upgrade price for the 2008 version is only $6.95 which includes three months of free technical support. You can buy the upgrade from: http://www.macecraft.com/eshop/jv16powertools2008-upgrade/"
If you don't wish to upgrade, you can simply Uninstall PT 2008 and go back to PT 2007, you can download it from: http://www.macecraft.com/downloads/jv16pt_setup_hb.exe_1.7.0.422