Can I Play Ps3 Games On 720p On Simple Flat Tv Using Component Av Cable?

I think the AV cables supplied can only produce 480P(DVD quality) picture or at most 576P. 720P means you are entering HD lines. HDMI cables are meant to handle HD signals. Try a HDMI and you will see the difference.
Also, your TV should support HD. I am hoping by ‘Simple Flat TV’ you mean a LCD or a PLASMA TV and not normal CRT’s with a flat screen.
Check for the terms ‘HD ready’ or ‘Full HD’ on your TV or else check for a HDMI slot behind the TV (It’s a single rectangular slot). If you have it, then only can you view HD picture via a PS3.