is right, your lenses will determine a lot more about your pictures than your camera body will.
The K100D is definitly a good buy and great value for the money.
Also there are a lot of nice lenses on the 2nd hand market for a nice price, which might help you a lot too.
The SR is a plus aswell.
Do keep in midn that there is no vertical grip for the K100D.
There is one for the new K10D and I think there are grips available for Canon and Nikon cameras too. So if that's important for you you might want to look at those.