There are different programs out there that will tell you what hardware (the equipment) and software (the programs) you have. If you are like most people when you bought your computer you knew and saw the specifications of what it had, but most likely threw that paper away or have no idea where it is now.
There are two free programs that I like that will tell you what is in your computer.
Belarc has been around a number of years and is a free program for personal use at belarc.com When you run the program it will come back and give you a report on all the equipment connected to your computer and all the software and the CD/product keys for each. Just for this last part I would suggest you keep a copy of the report.
A newer program is Speccy and it is free for personal use from Piriform.com It gives you a detailed list of all the equipment in your computer and has a friendly interface. However it does not tell you about your software. Piriform also makes ccleaner which cleans your computer registry and Recuva which will recover deleted files on removable media like usb drives and on memory cards we use in our phones and camera.
In both products look for the free software at their websites. I have used both programs successfully and they are both easy to use.