I am also looking at a DSLR and while most everyone seems to look only at the Canon I have a Pentax SF7 with K mount lenses so was interested in getting a Pentax DSLR so the lenses didn't go to waste. My local photographic dealer is also into Astronomy and he recommends the Pentax K20D which is a lovely camera and has live view and remote control. However I don't know if it gives the same level of control as the Canon from a laptop. The Canon 40D is reviewed in BBC Sky at Night June 2008. The reviewer concludes "For the purpose of astroimaging, the 40DH is a dream DSLR." The "H" is the Hutec modification to replace the ir filter. I expect details on what the Pentax K20D software can do is on the website
www.pentax.com.au. I haven't taken the time to look it up yet.
I noticed in a seperate thread a discussion on lenses - kit one's with the camera vs Sigma, Tokina etc. I have a Pentax and a Tokina lens and the Tokina is better for sharpness. Haven't tried them for astro so don't know how the CA compares.