No sound on windows 7 ultimate, but it has worked before!

Hi, I'm using a macbook air OS X Mountaint Lion (10.X.X <- not sure about those numbers since I'm on the windows 7 atm) and I've tried to install windows 7 ultimate(32-bit) a couple of times, and the very few first times it did work, installing it, and getting the sound and internet, everything working.
But when I realized I didn't have enough space and had to re-do it, I removed windows 7 again and re-installed it, this happend a couple of times because I needed 50gb, but ended up having about 45 everytime I finished installing windows 7.
And for some reason I just couldn't open set-up.exe anymore through my USB with the boot camp support software in it. Note, it did work before, but after a few re-installations, whenever I try to open the set-up.exe this is what shows up : This version of this file is not compatible with the version of Windows you're running.

I mean it has worked before, I did exactly like all the other times, but I did notice one change from the first times and to the times where errors started occuring. It was that when I'm installing windows, I get to choose between windows 7, basic, and all the other ones, including windows 7 ultimate. But the very first times I installed windows it automatically chose Windows 7 Ultimate, I couldn't chose which one I wanted.

I've tried to install boot camp support softwares through apple's website on the download page, I've tried 4 different and only one, almost worked. I could open the set-up halfway and and then somehow I couldn't install anything, so I decided to try and open all the maps and install the softwares manually, which provided me with internet atleast, some worked some did not work such as Nvidia. But I need the sound! Help me?

Sincerely Kenny