et hurtigt søg på google kunne give dig denne info :)
Okay, all good questions.
The first file on the list is the .ISO (DVD image) of the Service Pack, it contains all three versions (IA, x64, x86) and is meant to be burned to a DVD and installed from there.
The next six files are the symbol files for the various version and languages. They're used to debug the Service Pack and aren't really required unless you start running into problems and want to try to find the solutions on your own.
The last three are the Service Pack itself - three versions for the three different architectures - IA64 for Itanium processors, X64 for 64-bit Windows 7 and x86 for 32-bit Windows 7.
Windows 6.1 is Windows 7. 6.1 is the Windows version number while Windows 7 is just a marketing name. If you don't have SP1 installed your Windows is Version 6.1 Build 7600. After SP1 it'll be Version 6.1 Build 7601. From a Command Prompt type in winver and see what it says... Rather confusing isn't it?