The solution is to use a 64-bit Windows 7 client to add the printer driver as follows:
- Start the Print Management administrative tool (printmanagement.msc)
- Add the Windows 2003 file server as a print server
- Add the 64-bit driver
Please note that the 32-bit and 64-bit drivers need to be named the same. So, with different version of the driver, you may have issues.