From Via Arena:
VIA have led the way in pioneering the unified driver set. The VIA 4in1 drivers, often known as a VIA 4in1 service pack have been the mainstay of VIA systems for years - optimizing stability and comparability. Today (10 December 2002) is an historic occasion, as VIA changes the name to VIA Hyperion 4in1 drivers and launches the driver set, optimized for performance for VIA's latest chipsets. The name Hyperion will most certainly supercede the name 4in1 all together in the future, but "4in1" has been kept in the name for identification sake. The version numbers also continue on from the 4in1 driver series so as not to confuse our customers.
This is meant to be the new choice for KT400 and P4X400 chipset users. Improved performance. More information about the Hyperion improvements can be found here

So all you 3dmark2001SE score monkeys can get a little boost