I had a 20D which AFAIK should give pretty much identical IQ to the 30D and I was very happy with sharpness, so, I think, with respect... it's possibly your technique or how you sharpen your shots. Assuming that you are selecting an appropriate aperture, shutter speed and ISO maybe the problem is sharpening?
Remember that digital images need sharpening to look their best so the question is how to sharpen them and I suppose this depends upon what software you're using.
It might be worth posting some example pictures together with EXIF and also details of what processing software you're using and what your sharpening is set to.