Altering a voice, what can be done?

[Rudyard]

Im trying to make a little fun movie for my kids but this could also be used for any video.

When I record my voice to the PC can I alter it somehow to sound for example nice and deep like James Earl Jones (darth vader) or like the voice that plays over movie trailers when your at the cinema?

Or in general can much be done to a voice that doesnt sound all 'computery' if that makes any sense?

Also what programs would be needed? I have Sony Sound forge, cakewalk sonar and can get access to Adobe Audition.

Im not really sure where to start with audio and I cant literally make my voice do a thousand voices like the bloke off police acadamy

I record to my PC via an audio interface which I plug my mic into.

[AlanHK]

Audacity is freeware.

It has a number of filters, like "Bass boost", "Change pitch" that might be what you want.

If you have another sound editor, look at its filters/effects menu and see what it has.