From what I have read:(again from Holcom Networks' press release)

Users of DataSecurus PCs can access both secure classified networks and unsecured unclassified networks (i.e. internet) from the same computer without the possibility of unauthorized access or loss of classified data.

 Previously such users required 2 physically separated PCs on the same desk.

This patented technology known as the Sentinel System is praised by DOD, Nato and other Federal agency employees.

Any comments on how big this could be?