Oh, I'll post a guide. I've been planning on it, I just take FOREVER to do anything in regards to this computer. :P

The optical drive is already in the lower slot, but I will need to remove more of the upper, back area of the chassis to fit a new cooling unit (of any kind!) on the 9800 Pro. That's actually my last priority, as I'd rather get the computer to be 100% stable and quiter first.

Knowing that air is key, and after removing the upper optical drive bay door, I'll have two vents in addition to any and all fans: the speaker hole (the speaker has been removed, and I will be putting a fan in that area, which may force me to cut down that bizarre wall coming up where the AirPort card slides in) and the drive door.

The ugliest parts of this computer so far are the cut optical drive chassis (it's not a straight cut, but maybe a few hours of grinding could fix that...) and the fan speed controller which is basically just taped into the case. Yay!
DP 1.08GHz PMG4 MDD, 1GB PC2700 DDR, 200GB ATA (16MB, 7200RPM), Radeon 9800 Pro (256MB)