David, as a starting point for planetary - I suggest that you get a nice, little cheapy Philips SPC900NC toUcam/webcam. Most planetary guys start out there. It will capture video, not individual images like your SLR. Specialised software like Registax will break that video down down into thousands of frames, which are stacked to create a 'super frame' for want of a better term.
Also, because you're trying to use a SLR with a refractor (correct me if I'm wrong), you'll definitely need to invest in a barlow if you persisit with the SLR setup. For example, guys that use large mirrored scopes (newtonians) for high resolution planetary typically work commonly use the 5x Powermate by Televue, connected to their cameras, to reveal fine details on the surface of the planet.
Here area a few primer articles to get you started:
http://www.iceinspace.com.au/63-431-0-0-1-0.html and
http://www.iceinspace.com.au/63-306-0-0-1-0.html.
Good luck. Logan.