Orlando,
Without having some example photos or more details, we are just speculating, but John may be right. If you are using the "auto" mode on your camera, you may want to explore the manual settings and learn about things like aperture, shutter speed, depth of field, etc. Most recent digital cameras (point & shoot or dSLR) are capable of yielding sharp pictures in capable hands.
If you are looking to learn more about photography, I can recommend
Understanding Exposure by Bryan Peterson as a good learning tool.
If you decide to venture into digital SLR's, just about any recent model from Canon, Nikon or Sony are very good cameras. However, simply buying a dSRL will not result in any better pictures than you are getting with your Sony if you do not understand the basics of photography.