LabVIEW 2011 has only a few toolkits that work as a 64-bit installation on 64-bit Windows 7. You can see the list of the supported LabVIEW 64-bit toolkits at:
With regard to Device Drivers, the same Device Drivers DVD or download (4.8GB) is used for 32-bit and 64-bit LabVIEW. When you start the Device Driver installation, you will be prompted for each available items whether you want 32-bit or 64-bit.
National Instruments notes that you can install both 32-bit and 64-bit LabVIEW on a Windows 7 x64 system, and virtually all toolkits are said to work for a 32-bit LabVIEW install on a Windows 7 x64 (64-bit) system. There is said to a bit a of a performance penalty for using 32-bit LabVIEW on 64-bit Windows 7, due the Windows on Windows (WoW) emulation layer, but I haven’t yet found any benchmarks supporting what the difference is. Perhaps something I’ll post on in the future.