They're drivers for 64-bit Windows, (or 64-bit Linux, for some of them) to
let the said operating system operate pieces of hardware which don't have
drivers on the operating system CD.
For example, the 64-bit beta version of Windows doesn't have 64-bit versions
of all the device drivers that are on a retail Windows XP or Server 2003 CD.
One of the reasons for producing the beta OS is to let hardware
manufacturers
write and test 64-bit drivers. 64-bit Windows can't use 32-bit drivers IIRC.