Professional looking with CC particle world is somewhat possible, but not easy. I’ve seen some very good explosions using only CC particle World (not hollywood movie quality of course, but more realistic than you would see in a video game). My advice would be to look at some stock footage of an explosion. Study it. Look at the rate at which the explosion occurs, how the bright parts emit, and how the darker parts emit. It will require several layers with the CC Particle World applied to them, all with different purposes. You may have to blur and darken some layers, add glow effects and use the Add blending mode to others. You will also want to add an adjustment layer on top of all the layers with a curves adjustment applied to it. It will take lots of time and tweaking to get it to look decent. Trapcode Particular would make it a lot easier. If thats not an option, I wish you luck. You might even be able to find a project file to download off the internet where someone has done all the hard work for you.
Jon Geddes
Motion Graphics Designer
http://www.precomposed.com