Hi Duncan,
My 2-bob's worth.....I always shoot in RAW (.CR2). I accumulate my shots onto one of several CompactFlash cards, which I change out regulary through the night.
I view the RAW files in the Canon program that came with my 20Da - I presume the 1000d came with something similar.
In that program, I check, and adjust the camera if necessary, to get an exposure where the histogram is well away from the left-hand egde of the graph, but not too close to the right-hand side.
I then adjust the view to 200% to check for tracking, polar alignment and focus issues. If the stars look good at 200% you're doing the right thing.
From there, I move onto IRIS - which is free.
http://www.astrosurf.com/buil/us/iris/iris.htm
Although there is a steep learning curve involved, it is well worth the effort of perseverance. There is a yahoo group dedicated to Iris, and a couple of excellecn tutorials included to help you work through the process.
Iris converts the .CR2 format into its own .PIC format. It carries out all the required functions - darks, flats, alignment, stacking and stretching beforeyou end up with a .PSD format which you can finish off in Photoshop. Saving to .TIFF or .JPG only at the end.
There is a learning curve for sure, but with practice, you will improve. The stars will be out there for a few years yet, so no need for haste. Think of it as character building!
HTH,
BC