Well I do everything using a mouse, I've never had a tablet. Thinking about getting one maybe, who knows... but I'm so used to drawing using a mouse that i really don't feel much need for a change. I usually do my straight lines in MSPaint, since I hate doing that using Photoshop. MSPaint is so simple and so intuitive that it makes it easier for me. I use photoshop for alpha channel, organising elements on layers and adding transparency to textures (that's cheating, I know, so Ive been trying to avoid it lately). I use transparency for shadowing, glasses, water and for roof textures.