Because it does not work
When you test, then please make sure you test using a non-administrator user,because there is no chance my son will get administrative rights.
Minecraft 1.3.2 itself is working properly on windows 8 professional. minecraftforge-universal-18.104.22.168 chokes when it is downloading files.
I tried a few times both using my own mod installer (using scripts to add files to the minecraft.jar) and completely manually. Each time with a freshly downloaded, totally clean Minecraft 1.3.2.
I did the same thing on a Windows 7 professional machine where everything worked ok.
Maybe it's time to test on Windows Server 2012 too
Oh, and maybe also consider to use windows compatible line breaks in your readme files. Windows uses carriage return + line feed, whereas unix compatible systems uses only carriage return, and this makes your readme files pretty hard to read.
Fantastic mod you are building btw.