Plug-n-play works great when it works. When it doesn't, sometimes you have to Plug-n-pray!
Also, if you are confident working inside the computer, you can remove the expansion cards and then reseat them one at a time. Windows will have a better chance of avoiding device conflicts this way:
1. Turn off the computer.
2. Open the case.
3. Remove all the expansion cards (sound card, modem, etc.) except for the video card.
4. Place the cards on a sheet of paper or a paper sack (not on a metal surface or plastic).
5. Power on the computer.
6. Shut the computer down and reseat only one
of the expansion cards.
7. Power on the computer and check Device Manager to verify there are no conflicts.
8. Shut the computer down and reseat another expansion card.
9. Power on the computer and check Device Manager to verify there are no conflicts.
10. Continue the previous steps until all of the expansion cards are working without a conflict.