Video Card?

In my first post I mention the desktop PC that's telling me that my OS is " NOT GENUINE "

the-mekanic not only answered my question, he put into perspective virtual every other problem that I run into by mentioning that " no longer supported " may trigger other problems.

That being said, The older Dell that this one replaced was taken down and stored in a large temp controlled closet, top ventilated shelf, where it has sat for over 5 years. I have no idea why my brother took it off line and stored it there. I pulled it down and tried to fire it up. as soon as I plugged it in, the CPU went on without a need to push the start button. But there was nothing on the screen. I took the monitor ( also a Dell, in fact, a smaller version than the one I'm looking at now ) and plugged into the current CPU and it immediately lit up. I tried the bigger one on the older CPU and it remained dark. Upon opening the case I saw that a small fan on the video card was spinning but no image on the monitor.

Assuming that the card went bad at some point in time; perhaps this is the reason it was taken off line and stored? I may never know; is it possible to buy a new card ( I hear people saying: "WHY WOULD YOU WANT TO" ) to replace the one in it now and if all else is good, can I expect it to light up the monitor?
My old files are the main objective.

Might as well mention that I suppose that I can pull the hard drive and mount it in an external case and unless there was a major crash, see my files that way. If that is incorrect for some reason please explain also.

Much appreciated!