Hi Bob.
If you want to image Solar System objects, I wouldn't recommend any of the DSI's. I'd definitely recommend the ToUcam 900nc as a starting point for webcam based imaging of solar system objects.
It's the best budget webcam on the market for that type of work, is very easy to use and can get very good results. There's also a tonne of information here on IceInSpace if you search old threads, about how to use them, processing images with them, etc.
You don't need a bigger telescope, yet. The ETX125 will deliver pretty good results on those objects. The main hassle will be the very long focal ratio for the smallish aperture. They're f/15 or something aren't they? When you put a 2x or 3x barlow in, there's really not a lot of light coming in for the focal length so you'll need to use longer exposures and a higher gain to brighten the image enough during capture.
It's a great way to learn the art though, and with practise you'll get good results. THEN you can upgrade to a 12" newt on an EQ6 or a C11 or something similar
btw
to IceInSpace!