G4 processor and what is Altivec?

[Leon Sargent Jr]

What does the Altivec processing engine do for overall performance is OS X?
Does the Altivec engine work only on graphics both 2D and 3D does it work on
widows and scrolling?  I know it help in processing in Photoshop and I would
assume other programs that are graphics intensive but what does it do for
the OS?

I have a B&W G3 450 with Radeon 7000.

Lee