I use the web site "Can You Run it"
http://www.systemrequirementslab.com/cyri
It installs an app that will test your computer to see if it will run the game you select. It shows both minimum and recommended system requirements for the game. As an alternative you can skip the test and just display the system requirements for the game. Here are some examples:
Starcraft II
System Requirements (Recommended):
CPU Speed: Dual Core 2.4 GHz Processor
RAM: 2 GB
OS: Windows Vista/Windows 7
Video Card: 512 MB NVIDIA GeForce 8800 GTX or ATI Radeon HD 3870 or better
Free Disk Space: 12 GB available HD space
StarCraft II: Heart of the Swarm
System Requirements (Recommended):
CPU: Intel Core 2 Duo E6600 or AMD Athlon 64 X2 5000+ or better
CPU Speed: Info
RAM: 2 GB
OS: Windows 7/8
Video Card: NVIDIA GeForce 8800 GT (512 MB) or ATI Radeon HD 4850 or better
Sound Card: Yes
If I were you I would only look at the recommended system requirements since only having the minimum system requirements may work but limit game play. Remember that even the recommended system requirements for your games you have now may not be adequate for games you want to buy in the future.
For example I built a computer in late 2009 that met all the recommended system requirements for the games I had then. By 2012 I had to buy a new video card because the one I had was not adequate for the new games I wanted.
It comes to getting a better more costly computer now that lasts longer before a new one is required or getting a less costly computer that is adequate now but may be obsolete in a year or two. The more expensive computer may only require upgrades to be usable for future games. The less expensive computer may prove impossible or too costly to upgrade to keep up with future games. In this case a totally new computer would be the best choice.