As the others have already pointed out, getting your polar alignment right is the first step, use an autoguider and make sure your focus is right and you could reasonably expect a single frame not much different to the one I took at Astrofest
http://www.iceinspace.com.au/forum/s...&highlight=M42 that image is a single frame, Iso 800 5 minute exposure on an umodded Canon.
While that image is by no means decent, it's a good starting point, lesser exposure will bring out the blown highlights in the core, so a mix of exposures is the way to go.