I have found if I leave one spot open on the first page, a new install will go there. I can then move it to another page. I keep at least one spot open on each page for moving of icons. By doing this, I don't get any re-arranging.
New installs should always go to the first open spot on the springboard.
This will of course cause the other icons to move one space (if one app. is installed) depending on where the open space is located but that's as much icon moving as should take place.
Hmm... When I restart my phone or install an app. All of my icons rearrange themselves. My Springbaord only had icons on the top and then blank icons to fill the rest of the page. Odd.