Motorola V400
Help with wallpaper...
First, the picture will look best on the phone if it is resized to 176x220 pixels since that's the exact size of the LCD. Anything else will be resized to fit by your phone and won't look as good.
Secondly, what quality (compression) level are the pictures at? Anything lower than about 85% or so (lower is more compressed, higher is less) will start to make the picture really blurry and blocky when seen on your phone. On the computer it may look just a little off, but it will look worse on the phone. On the flipside, if you have the quality level high then the picture will generally look BETTER on the phone than on your computer.
Hope this helped.