Donald, you really don't need any more than you've got. I shot that one at 1600 ISO, about 20 secs, and got the stars back into circles instead of the short bars that the earth's movement causes over a time exposure by using Focus Magic's Motion Blur filter. Unless you're doing deep space or accurate measurement-type astro imaging, this is perfectly adequate and means that an equatorial mount is no longer essential for pictorial star shots.
I shot that one on a 35mm lens setting, so even an extreme tele lens isn't necessary. A 200mm lens with a 2x adapter for closer stuff can also get surprising results.