This is the error:

[Window Title]
C:\Users\Sergio\Desktop\Things\Setup.exe

[Content]
The version of this file is not compatible with the version of Windows you're 
running. Check your computer's system information to see whether you need an 
x86 (32-bit) or x64 (64-bit) version of the program, and then contact the 
software publisher.

[OK]

I'm running Windows 7 (64bit) Ultimate and have installed this service pack before (2 days ago) on another machine with similar specs and the same exact OS software.

I've tried mounting the .ISO file to a virtual drive and installing from there and I get that error.

I've tried mounting the .ISO and copy pasting the files to a local folder on my drive and then running the setup.exe application, and I get that error.

I don't know how to proceed but can provide any additional information you require from me. What can I do to fix this?

Edit

If I right click Setup.exe and Run As Administrator, I get the following error:

[Window Title]
C:\Users\Sergio\Desktop\Things\Setup.exe

[Content]
Windows cannot find 'C:\Users\Sergio\Desktop\Things\Setup.exe'. Make sure you 
typed the name correctly, and then try again.

[OK]

I've already tried re downloading the ISO from the site, but a quick check of the bytes of the file assures me that the ISO on my drive is 100% correctly downloaded. I get the same amount of bytes in size from the downloading ISO (as Opera reports).