InfoPath 2007 comes with Visual Studio for Applications. I don't recall if it installs with the default installation configuration -- you may need to walk through your Office install again and select Custom Configuration and select it.
Visual Studio uses Visual Studio Tools for Office. I believe those are also a separate download. If you choose to use VS for your IP code, you need to create a new project in VS and then you can select an InfoPath Template for the type. You are given the option of selecting an existing template, if you like.
Hope that helps!