For displays, the dpi doesn't matter. The only thing that matters is how many pixels you have. DPI matters when printing though. If you had 72dpi and 10" wide (72 x 10), that would be 720 pixels wide, which would be fine.
As most screens are at least 1024 pixels wide, you can comfortably fit 900 pixels width on the screen if you want a larger image on the screen.