Hey Zentron,
You're using Photoshop, right? When you make a new document, take a look under the Film & Video presets (I think that's what its called, something like that.) There's should be a selection of sizes that are standards for film and video work.
There's not really a DPI equivalent in film and video. The pixel ratio is it, that's all you have. So if you're video/film image is 1280 pixels across, it doesn't matter what pixels/inch it is. If you're making a moving image, at some point, you're going to have to take your photoshop image into an editing program or a compositing program, something that outputs video. When you do that, pixels/inch doesn't even play a part of it. It's only going to care about the pixel width and height.
Here's a video resolution chart.
http://en.wikipedia.org/wiki/File:Vecto ... dards2.svgIt does not include film resolutions, the most common of which is generally called "2K", which is 2048x1556 pixels.