First of all, thanks for uploading the files! I was surprised to learn that there is supposed to be a .NET Framework version 4.0.30320 for Windows XP. I couldn't find anything about it in any official source. In any case, your installer "Microsoft .NET 4.0.30320 Full" is the same one I have, and it has the number 4.0.30319.1. Presumably, at least for Windows XP, there is no version 4.0.30320. You can find out your current version installed with the following command:
reg query "HKLM\SOFTWARE\Microsoft\NET Framework Setup\NDP\v4\Full" /v Version
Although it is actually Microsoft .NET Framework 4.0.30319, I have nevertheless found a reference to version 4.0.30320 in Windows XP. Apparently, the Client Profile and the Extended are assigned exactly this version number: