I hate to be the bearer of bad news but I would seriously look into returning that. It's probably one of the worst options you could pick. Whoever sold you that computer is not to be trusted.
If your budget is only $300 you should look into used stuff. There are good deals to be found (people buy gaming cpus they can't afford and pawn them all the time) but there are also lots of peeps out there trying to swindle you.
You want something like this:
http://www.kijiji.ca/v-desktop-computers/oshawa-durham-region/dell-inspiron-660-w-6-month-warranty-upgraded-for-gaming/1053568564?enableSearchNavigationFlag=true
Obviously my area, but you can find something similar near you. Older gen i5, Radeon 7770, upgraded PSU, 8gb ram... $350 CAD (note: worth our money isn't worth shit right now, that's less than 300 US). That computer will be leaps and bounds better than yours.
I guess if it's only infantry you play then it doesn't matter that much tbh. If you want to play other games, aim for at least an older i5 processor, and make sure it's the desktop version. That way you have a decent base to work with. Then you can always upgrade the video card down the road for cheap (~$100) and it should last you a while.