Heya Pete!
Welcome to IIS!
I have an unmodded Nikon D90 and i reckon I get some beaut pics from it at my level of expertise. They are not poster material, but in my own ( heheheh) opinion they are close. Processing the pics is another story........
Eventually, when I get round stars via accurate polar alignment, proper processing techniques and proper guiding via PHD........I'll look at maybe Maybe modding my camera ( even though that seems to be a non existent thing for Nikons...) I guess I'll have to step up to the dedicated astro CCD's
Cheers
Bartman