DBS Terrain Awareness and Warning System (TAWS) is available for purchase:
DBS TAWS for FSX at 4SimShop.com

AWS (Terrain Awareness and Warning System) helps to avoid Controlled Flight Into Terrain
DBS TAWS system can be used with any aircraft or helicopter in Flight Simulator X.
As a universal system - DBS TAWS can be simply added to an aircraft as a standalone
window or adapted to a specific panel by editing panel.cfg file and dbs.taws.cab xml gauge.

This addon requires MS FSX Service Pack 2.
If you have problem installing this program, please, try to install VC Redist, which can be downloaded from here:
Microsoft VC Redist