Is it possible to use WPF and Delphi 2007/09 win32?
Yes, you can, with a product called "Hydra" from RemObjects:
http://www.remobjects.com/hydra.aspx
They have a demo showing embedding a WPF graph in a Win32 application.
As Ken White notes, you can develop all your .Net stuff in Delphi Prism. It can then be leveraged in Win32 using Hydra if you like.
You can take a look at TMS .NET Interop Tools Pack. It contains components to display xaml and xps-files in your delphi-application. How well this works - and if it works well enough to switch from vcl to xaml, I don't know...