The patch for Morrowind is like any other game patch. You go to the publisher's website, look for Support, download the latest patch, and then run it in your game directory. Note that you only need the latest patch. So if you have Tribunal as well as Morrowind, you only download the Tribunal patch, because it's an add-on that in itself patches the original game.
As for things to get or stay away from: post your PC "stats." I'm surprised you don't know how to get these, since you already have a PC.
