DVD stills capture app needed ASAP

Hi All

I'm doing some research and need to capture stills off various DVD films.

Can anyone recommend a good program to do this? Ideally with the best
image quality possible.

I downloaded DVDCapture but I cant extract the .SIT compressed file ( it tells me it cant use Stuffit Deluxe as it is a Power PC application -- anyone know a way around this so I can extract it? )

Many thanks all