Hey guys, I'm about to purchase some B&W film to use this summer for street- type photography. In the past, I've traditionally used ISO 100 film, so to eliminate potential graininess if I want to enlarge. However, I see a lot of people here suggesting ISO 400 films, particularly Tri-X and Ilford. Is the graininess factor not as high in these, or does 100 vs 400 not differ substantially compared to color films? Help me out here. I'd hate to get the shot of my life with 400 film, only to have graininess ruin it. Also, if you don't mind, suggest some appropriate films for each speed. Thanks.