To capture marketshare. Remember when Netscape Navigator was King? MS gave a free copy of IE away with every version of OS, and they finally did in Netscape. Now everyone has to use IE (though Firefox is trying to do the same to MS).

And MS wants their version of Google Earth to become a standard, so they are allowing people to build models for it using a free copy of trueSpace, just as Google does with the free version of SketchUp.

I suppose there's a lot at stake in the "Virtual Earth wars."

Oh, and it appears the last version of trueSpace sold for under $600.