If your images are at least that size (960x800) or larger, your good to go, but if they are smaller you may wind up wanting newer images as they may get pixelated on the Incredible screen. There are a few good wallpaper sites and threads (including one right here in PPCGeeks) if you want to look around, or if you have an image/idea in mind but don't know how, you can always ask or post it here and people will help you out with it.
http://forum.ppcgeeks.com/showthread.php?t=119941