Skyrim - High, GMod - High, DayZ - High, City of Decate - High, BF3 - High, TF2 - High.http://pcpartpicker.com/p/fsQH8d
And would I be able to install the operating system using a bootable USB Flash drive?
YOu won't be able to play high. Most of those games, you will just about be able to play on low to med. To play on high at your budget is well, tough. However you can play on med-high if you get this: http://pcpartpicker.com/p/yDBBhM
Get this if you want high settings on atleast some of your games. Please extend your budget by 30 bucks. Coz there's gonna be a helluva lot of difference in performance between these two pc's.