Normally, use 32 bit(x32) driver
  CT-S4000_x32_v1583.exe
If you know you need 64 bit(x64) driver, please use x64 driver
  CT-S4000_x64_v1583.exe

Driver for 32bit(x32) is for
  Windows 2000
  Windows XP
  Windows Vista
  Windows Server 2003

Driver for 64bit(x64) is for
  Windows XP x64
  Windows Vista x64
  Windows Server 2003 x64
