try this link:
http://zone.ni.com/idnet97.nsf/9b2b33e1993d877786256436006ec498/137ff36eaf5ada68862568ab005fbc2a?OpenDocument
PS: You need to be registered user to download the drivers
If the link doesn't bring you there, you can visit Instruments Driver Network under NI Developer Zone. Do a search for the FLUKE 8840A
Hope you will get what you are looking for over there.
Regards
ian.f k