Here is how I do it (and how we do it at work on our console games).

Create the image at the screen resolution that you want. Then resize the image to 256x256 or 512x512. Draw a single quad that fills the screen with this texture on it. Be sure to set bilinear filtering to enabled.

Another way to do it (which some other console developers use), is to create the image at the desired screen resolution. Now cut the image into 256x256 or 512x512 sections. Use these textures on 256x256 or 512x512 quads drawn on the screen.

Using either of these methods means that all your textures are power of two, resulting in maximum compatibility. That is, these methods work on every 3D card out there.

I hope that makes sense.