Hey manborn - I posted this in one of your older thread, but I'm guessing you'll not see it there.
I'm also trying to replace the sn-324f (with the same model, so no bios problems for me) on my 200x since it stopped reading DVDs a couple of months ago. I assumed that I had to completely remove the top part of the case. I tried opening the case, and almost had the thing apart, but there is some kind of hidden latch along the right side right by the USB port that I couldn't free. So after much vexation I gave up (temporarily) and put everything back together - everything still works.
From reading your posts it appears you were able to get the drive out by only removing the three screws around the drive (2 back near the battery, 1 in the middle along the right side of the machine). Could you please provide some more info as to exactly what you did? If the drive will just slide out then that is much easier than disassembling everything.
Thanks