x64 versions of Windows do not support 32-bit kernel mode drivers. Microsoft's statements re: Vista are here (be sure to look at the errata at the bottom-- the article has a major mistake that it corrects), and the same is true for Windows 7 and Windows Server 2008.
There is no magic "switch" you can throw to allow 32-bit kernel mode drivers to work on an x64 kernel. They won't, period. (Yeah, yeah-- I suppose somebody could write some kind of ugly shimming system to make it possible, but nobody outside of Microsoft would have the necessary documentation to write such a thing... Besides, it's easier just to run a 32-bit OS under virtualization in a 64-bit host if you really need that...)
With respect to printer drivers, Easy Print is Microsoft's answer to the nightmare of client-side printer drivers in a Terminal Services environment, but you need Windows Server 2008 on the Terminal Server machine.