[SDK2003]

jon_s - What camera are you using ??

Looking at your photos you need to use a faster shutter speed, something like 1/250 - 1/320 should do. Also, make sure you follow (pan) your subject. As soon as they come into view start tracking them through the view finder, when they reach the 'target' zone press the shutter button but continue to track them. This will give you a sharp subject with a blurred background.

If you don't follow the subject you'll need a very high shutter speed of at least 1/1200 and you won't get blurred backgrounds.