This tutorial should help you change the color of the inside... and border of the selection box in Windows 7.
I made it because it took me a long time to find anything relating to this, and thought it was a hex change or something, but when i saw it was easy enough for normal people without special software to do, then i made this tutorial.
I tried this edit on a regular Vista 64 machine, and it totally messed up the computer. So unless you have a patched system and know what you are doing in Vista, i would not recommend this. I assume it was because i did not patch some files or something, when i edited the Aero.theme file and saved mine in the folder and clicked on basic, everything turned black. So, just use on 7 unless you are looking to have fun. And as for XP, i assume it might work on that though.