Whats more effective and get results in a month?

Ok im on the third week of p90x however the cardio dvds like kenpo and them are way to easy and i want to work more on my shoulders arms and chest instead of one time a week and i have a good diet pretty much with the protein powder and stuff im like 14% bodyfat and i wanna reach to at least 9 or 10% by aug the 4 or 5 so should i go to the weight room and work on arms shoulders and chest for two or three days out the week and do an hour cardio every other day ??? Which is best help me??