If you're referring to the old Vista search feature, I apologize as I know of no program to bring that back. As for how the Vista Search works, by default, it directs you to the indexed locations first and foremost. When I run a search on a specific file, I usually recommend going towards the folder you last recall, setting the computer into advanced search, choosing non-indexed locations as well, and then searching.
As for the GUI, if you're referring to the general appearance of Vista. If you want to remove Aero and go back to the classic Windows view.
1. Right click your start menu.
3. Start Menu Tab.
4. Ceck in classic Start Menu.
5. Click Okay.
6. Right click Desktop.
8. Windows Color and Appearance.
9. Open Classic Appearance Properties.
10. Choose Windows Classic.
That should be it for the classic appearance. I'm quite fond of Aero and such.