I happened to have an Adaptec AHA-3940UW-card lying around, and wanted to use it with Windows7-x64 (in order to operate a DLT-tape drive). Yes, I am using good-old tapes for archiving things - I have high hopes that the data on the tapes will last for decades. Now the trouble was - I was unable to find a driver for this card. It seems that only x86-drivers are available. I was about to resign (and either install Windows7-x86 or buy a new card) - when I ran across this thread.
For me this driver works like a charm - I haven't tested it with a hard-drive or so, but with my trusted DLT-tape-drive it works flawlessly.
Adaptec78xx_x64.rar (45.34 kb)