Renoir,
there is a program called Track It that runs an inventory on your system. You can download the trial version and run it on your computer. It tells you a lot of info about your computer like hardware installed, software installed, all .exe's on your system, etc. I'm not sure about the .dll's registered, but is has a lot of other info. You can download it at www.blueocean.com
I've used it in the past and it's quite useful.

Bryan