The DLLs themselves contain no specific information on a users system hardware configuration.
At best, from the DLL files, you can determine;
version of Windows installed,
installed Windows updates,
hardware devices installed,
installed application programs.
However, from just the DLL files, only the version of Windows will be complete and accurate.
In the Visual Basic archives at Tech Republic's sister site www.builder.com.com is an article and code for gathering system resource data.
As to what each DLL does, there are various resources. I believe you can find details for most of Microsoft DLLs by searching Microsoft's site on the DLL name.
Remember, DLL stands for Dynamic Linked Library.
Each DLL is a set of resources for programs to use.
The bulk of the DLLs on most systems are components of the operating system installed.
The next catagory would be DLLs required for device drivers.
Followed closely by application program specific DLLs.
Most DLLs will be "registered" with the operating system in the system registry.
In a few instances, where a program requires an out-dated DLL, that version of the DLL may be in the program's folder.
Chas