You can switch the card and Windows will probably detect the hardware and apply CRT Emudriver automatically. This highly depends on the availability of other driver versions in your hard drive's driver store that Windows considers more "suitable". Anyway, in any case, your modes will be lost since they're tied to a specific device.
What you want to do is to backup all your modes (VMMaker, settings, video card, export modes). This way you can export all your already adjusted modelines to a text file. Then, once you have the new card up and running, restore the modes in the same way (VMMaker, settings, video card, import modes). Don't forget to press "Install modes" after this.