It all depends on how many frames you need to remove from the DVD. Understand the footage is already compressed and there will be a loss in Quality.

You could use WinDVD and simply step forward and use its snapshot feature. The files will be save to your PC in jpg format.

You could convert the VOBs to AVI and then import it into Premiere Pro and then export in TGA format.

Hope this helps.

or you could go to the best site on then net for this stuff:
VideoHelp

regards
Paul