really, seriously, use some common sense here. If you find an image on the internet you like, open it up in ms paint and use the rectangle selection tool to cut out a 480x640 selection. You can see how many pixels you've selected as you're selecting it in the bottom right hand corner of ms paint.
If you need even more advanced editing power, download gimp (a photoshop mimic) it's free.
Finally, searching for 480x640 in google image search returns many:
http://images.google.com/images?hl=e...h+Images&gbv=2
JEESH :P