Size a Wallpaper for Samsung Galaxy Tab 2 7.0
The screen size is 600 x 1024 pixels in portrait mode.  That's not the same as the wallpaper size, since the wallpaper is bigger than a single screen (try scrolling your homescreens left and right to see this).

Usually you need to double the width, and from what I can see online this seems to be the case for the Tab as well.  So use 1200 x 1024.