Is this the one that your son has?http://www.dell.com/us/p/inspiron-15/pd
My guess would be that you could probably skate by if you bottomed out the game's graphical settings. The system you have is pretty good, but might struggle due to the integrated graphics chipset, despite it being an "HD" card.
From that machine, try going to this link and running the Game-o-Meter. It will do a quick check on the machine to see if it is up to par...http://www.yougamers.com/gameometer/10361/