Hi, FWIW I have a superdrive in my eMac and just the cdrw in my iBook and I just bought an external dvd drive (check my sig.) I prefer the external and as far as the speed bump goes it takes me longer to think of what to do in flash than it does the ibook to keep up. With that said is it really worth the FSB and slight bump from 1.6 to 1.8...I looked at both before I bought my iBook and at this time I would go with the 1.6 since the screen size (I know you didn't bring this up) is most important to me OVER the other extras. Time is money to some but this slight diff. is not that big to worry and hey, $200 more to put into maxing out the ram 😀
One last thing is if you have saved up for the 1.8 and get the 1.6 look into the recons and the price just dropped more "compaired" to the price of a new iMac at the 1.8 price and that means even more goodies 😉