Heavy Racquets- These types of racquets are recommended for all players. The reason? Well for younger players who lack control these racquets help them focus more on placement then on "wacking the ball." These racquets are also recommended for other age groups because they are able to prevent tennis elbow. These racquets also have much power, but sometimes they lack control.
Light Racquets- These racquets are not highly recommended, because they cause tennis elbow. Light racquets have much control, but lack as much power as the heavy racquets. But today new racquets are being developed that are light, and very powerful.
Microchip Racquets?- The first microchip racquet by Head, the "Intelligence" has a mini microchip built in to control power and placement. The down side is that the microchip doesn't really make much of a difference in already good players, but if you have the cash the racquet is priced for $300 dollars.