The simple answer is NO. You are going to have to uninstall office 2007 and then reinstall 2003.
You could have some problems uninstalling 2007. There have been some problems with trying to uninstall 2007 when going through control panel. Which is the easiest way to uninstall programs. If you do have a problem with it let us know and we can find some resources. Are you using vista or xp. That can make a difference, too.
Cheers!