Epson doesn’t provide x64 drivers for their older scanners. However, the smart folks over at PlanetAMD64 have used the Epson Perfection 2400 Vista x64 drivers with success.

1. Go download the Vista x64 drivers from Epson’s website.
2. Extract the files to a folder.
3. Open the es27.inf file in a text editor
4. Locate the following line:

   [Models.NTamd64]
   %ES27.DeviceDesc% = USB.ES27XP.x64, USB\VID_04B8&PID_011B
   

   Change it to the following:

   [Models.NTamd64]
   %ES27.DeviceDesc% = USB.ES27XP.x64, USB\VID_04B8&amp;PID_011B<span style="color: #993300;">, USB\VID_04B8&amp;PID_010B, USB\VID_04B8&amp;PID_010B\5&amp;36C701F9&amp;0&amp;2</span>
   

5. Install the driver…
6. When prompted about the driver being unsigned, click on continue anyway.

That worked for me.