Ive only just started out in Astrophotography, recently perchased an HEQ5 for tracking to put my Canon 30D on... And i can tell you an EQ1 will be hopeless and a waist of money, you'll need at least motors to drive your mount, other wise youll have to manually track... and an EQ1 is wayy too small and wayy too wobly to take your D80, it would probably be worse than a tripod :S so, get something with a motor cos that woulod make your life soo much easier maybe EQ5pro or HEQ5.. I know its pricey and all, but i can tell ya it will all be worth it
Or, you can make yourself a barndoor mount, a cheap sollution for tracking mount....
Cheers,
Tony