|You said it yourself - "ATI Radeon HD 4200 Integrated Graphics". Integrated Graphics is NOT a video card, the graphics chips is built into the motherboard. As IGPs go, it's one of the best currently available but it's not really meant for gaming.|
The Pavilion P6230F is one of those screwy systems with the motherboard mounted upside-down:
Before you buy a video card, check your power supply specs (open the case & check the label). Kuwese recommended a decent card but if your power supply doesn't meet the requirements, you'll either have to upgrade the power supply & the video card, or go for a milder gaming card with lower power needs. It all depends on which games you wanna be able to play & how much you're willing to spend.
Have a look at this article:
Best Graphics Cards For The Money: November 2010