Yes, my son just told me it was something that comes into play when he is gaming, and now I feel like an idiot for trying so hard to track it down, when it is something that just automatically works when you need it!
The reason I thought I needed it is that I was originally a Mac User, and at the same time I got my last Powerbook, I also purchased a Panasonic Camcorder. Well, several years later, my Mac died, and having fallen on hard times, I had to replace it with a super-crappy Gateway notebook, which, of course has no CD/DVD drive. I have an external one, but again, the crappy quality shows in the fact that at less than a year old, it no longer plays CD-roms!
I could not install the software that came with my camcorder, so I went to try to download it, going by what the manual said about the necessary software. Foremost among those items listed was DirectX, but there was no in-depth explanation of where it might reside, and what it does! And the quest was on...
I did a bit more Google searching, and found that my horrific Vista OS came with a video program called Windows Movie Maker, which seems very similar to the iMovie software I had on my Mac. I found it serviceable, and am making due with it until I find something better.
I really want to understand my PC, but having only ever owned Macs, I find the learning curve on the steep side! I am embarrassed to have wasted people's time here, and thank everyone for their kindness in not pointing out how ignorant I seem about these matters.