I want to know if there is a difference in the magnification of a Canon PowerShot S3IS and a zoom lens for Canon EOS 30D.

From a 10x Optical Zoom lens to advanced Canon technology that automatically gives you the best shot, the 9.0-megapixel PowerShot SX110 IS packs impressive value. Advanced Face Detection Technology automatically sets focus, exposure, flash and white balance for beautiful portraits and group shots. Sharp, steady close-ups are easy with the powerful zoom and Canon’s Optical Image Stabilizer Technology. The slim and modern-looking SX110 IS is sized to go everywhere, and you’ll never miss a …

I don’t have enough knowledge about camera lens. I just bought a new canon camera EOS 50D. I am also planning to buy zoom lens but I have no idea what is the best lens for EOS 50D. Your recommendation is highly appreciated. Thank you.