Software "Switch" to Open GL Hardware acceleration?!

Many thanks to “Burning Rubber” for his advice on suppressing the line DVA=0 in the Win.ini file to restore hardware Open GL acceleration:
It works great!

By the way, use Execute MSCONFIG to cancel the line in win.ini, its very easy

Before I do that, I would like to know exactly what that line is for and what removing it will screw up.