I HAVE FOUND THE SOLUTION! ( I believe rofl)
After I have read every single post on the forums regarding this topic, both on EU and NA LoL forums, I have finnaly figured out the solution. Now, I don't know if it's going to work with the Windows 7 or Vista OS, but I'm almost 100% sure that it will on XP. The problem that people had all along is the following: the rads_user_kernel.exe file CANNOT run if you don't have installed Microsoft Frameworks. This won't be your issue if your on W7 or Vista because it's already installed on those OS',BUT NOT ON XP.
Just download it, install it and it should run without problems, as I have learnt by trying everything else. Reinstalling Windows, updating them, updating drivers, rebooting, etc. is not going to help, or at least it did not for me. So, long story short, just download the 3.5 Microsoft.net Frameworks and you will have no trouble running the patcher. Pretty sure that's the problem, because I have read almost every post regarding this, and I didn't notice anyone pointing this out.
Here's the link to download the 3.5 version (feel free to download the newer versions, allthough you don't need them on XP OS): http://download.microsoft.com/download/0/6/1/061F001C-8752-4600-A198-53214C69B51F/dotnetfx35setup.exe
Hope I helped.
P.S. If you already have frameworks installed, and it's still not working, then you can try everything else (updates,reinstalls,etc.), but I recommend trying this first, and then everything else.