Wallpaper size

Just set it as your wallpaper and try it out. If it doesn't look right, try a size bigger. If it's still not right, go bigger.

Or smaller. Just play around until you get what you like.

The resolution it says it is, is really what it is. In the browser it doesn't look that big, but when you put it as your wallpaper, it will fill up the screen, and look great. If you put it at a higher resolution than that, you won't see the whole picture on the screen, because it can't do it.

If the resolution of the image matches that of the screen (in your case 1440x900) and in desktop you have it set to center, then it should fill 100% of the screen pixel for pixel.

Again, your screen is 1440x900, 990 was the older high res powerbook.

This site also has some nice desktop images.
Lots of other cool stuff to!

You might want to consider getting the highest resolution pictures available; the key is in matching the screen width/height ratio (in the case of the MBP it's 1.6:1). I've got a bunch of older pictures is lower resolutions from my previous Macs, and when you try to scale them, they just don't look quite right. This is especially true of all the old 1024x768 pictures. http://www.macdesktops.com has a lot of pictures, and you can get them in a 2560x1600 format.

Yep, and if you cant find the exact right size, d/l a bigger one, and use PS or GC to save it in the size that matches your screen resolution....

in other words, scale it down, not UP....it's always a whole lot easier to discard data than it is to create it