Havok is much better than it used to be. Havok was new when Oblivion used it, so they hadn't got it down just right. Havok has gone through many upgrades and is pretty damn good now.
HAVOK WAS NEVER THE ISSUE !!! Read Ghogiel's post clearly this time and try to understand what is being said.
it's quite simple. you can actually change most, if not all, physics setting that affect this by modding the havok properties in oblivions meshes. off the top of my head, upping mass, inertia, linear and angular dampening change a lot of how that behaves.
All that was required for actors to fall realistically in Oblivion, FO3 or FONV was to alter the Skeleton.nifs RigidBody Properties namely Linear and Angular Dampening as these are the settings that apply negative force to an object in motion -> Beth set them a bit higher then realistic (most likely on purpose since it was done this way for EVERY actor) thus you get floaty falling lower them and everything works differently actor's drop quickly when dead.
Raising Mass makes then heavier -> obviously.
And raising Inertia make it so it takes more force to move them so they do not fly off into the distance from small forces -> arrows, melee attacks, spells....
Every one of these settings available to be altered to react in a realistic manner from day 1 ! so before you people go rampaging about whining about Beth using Havok again maybe you should get your facts straight first.