I couldn't get any of the existing XPwn guis to work on my Vista machine so I threw together this quick batch script that at least works.

Batch Script Only: http://www.filedropper.com/xpwnbatchscriptforiphone3g
Full Package: http://www.filedropper.com/xpwnpackageforiphone3g

Tested on two 8GB Rogers iPhone 3Gs on Windows Vista.

All credit for XPwn goes to the original creators who have done an amazing job