MMm well your in for a shock actually, as PC require alot more on your part for management and upkeep. They aren't just insert DVD and turn on the switch, you need to constantly upkeep on the video drivers, patches, etc. The advantage is you can use the PC for more then gaming, and can upgrade it when you can afford it, but there is constant upkeep (think of all the times some one has to change tires, fill air, add oil, fill the gas tank, replace windshield wipers, etc. on a car).
A simple solution is get a i5Core Walmart computer off the shelf for $349, add a PSU for $99+ to help support a video card for $129+ and probably a monitor (if not included with the computer) for $149 as well. That will leave you some flexibility for taxes and options for the PSU / Monitor / Video card you want. Then of course you need to run backup on the system right off out of the box, make your backup DVDs of your BASE image, install free antivirus like Avast or AVG, install malwarebytes, remove any bloatware by the maker, update all drivers and files, then run another backup of your 'tweaked system' before you buy and install any of the games you listed (best if done via Steam (www.steampowered.com) so you don't have to worry about losing the DVD or DVD key).
Get ready for random blue screens, suddenly slow downs, and numerous confusing issues that comes with being a PC owner.