Luckily, the majority of PCs can now receive the latest Call of Duty 4 Modern Warfare - Patch 1.3 without any problems, so you don't have to worry too much about this.
For example, if your PC is equipped with an older operating system, you will have no problem with this update, but if you have an XP platform, it's highly recommended that you install the latest Windows XP drivers so that your game can take advantage of all of the new features in this update.
Although this may not sound like a big deal, it can cause you a lot of problems as far as playing the game is concerned. Unfortunately, this new version is not compatible with the older versions of Call of Duty 4. This is actually quite simple to do and can be done by simply searching for your specific version of the game and then clicking on 'Check For updates' or something similar to this. In order to use the new features within the game, you will need to download the latest Windows update. It mainly adds new maps, game modes, perks, weapons and much more for this year's version. The patch has been available for some time now and provides numerous new features to the game. If you own a Call of Duty 4 PC, it is likely that you'll be receiving the new Call of Duty 4 Modern Warfare - Patch 1.3.
