The DCR-SR21 has a better image stabiliser type than most small sensor size camcorders that were released around the same time as it. This Sony camcorder has a Digital image stabiliser, whereas most small sensor size camcorders that were released more than two years ago have an Optical image stabiliser. Some compact cameras have digital Image stabilisation only, which simply boosts camera sensitivity (ISO) to obtain a faster shutter speeds to help prevent blur. No hardware is involved.
A Digital image stabiliser is in fact the worst image stabiliser type across all camcorders of a similar age and type to the DCR-SR21.
The best image stabiliser type across similar types of video camera is Optical.