It’s not shown on the Dell Driver download pages, but if you need the 64-bit touchpad drivers for the Latitude “D” Series laptops, you can grab it here:
Download Dell 64-bit Touchpad Driver for Vista and Windows 7
Alternative link: http://ftp.dell.com/input/R157047.EXE
The Driver should work on the following laptops:
Dell Latitude D430
Dell Latitude D630
Dell Latitude D830