SNIP Any standard IDE (PATA) drive will work fine in this, (not SATA!). You are lucky in your choice of machine as this not only has a faster IDE bus than the earlier G4's but it also does not have the 128GB limit, so you can install any size HDD you like (300-500GB are very cheap at the moment). Please be aware that if you want to run 9.2.2 there are a few things to watch out for, 1) if it is the second model MDD with FireWire 800 it cannot run 9.x. 2) you cannot use retail 9.2.2 install disks as they are missing some MDD specific files, you must use the MDD restore disks that were originally supplied with the machine. 3) as pointed out in another thread 9.2.2 cannot boot from a partition greater than 128GB. As memory is cheap I would suggest maxing it out to 2GB, the MDD will run 10.4.x very well (even better if you upgrade the graphics card). If it is 1GHZ or faster then it should also run 10.5, my MDD (867 O/C to 1.07GHZ, 2GB Ram, Radeon 9800 graphics) runs the current beta of 10.5 fine. Ben. SNIP Thanks for the sage advice. I don't think I will put OS9 on it. I have a Digital Audio that has OS9 on it...also two G3s with OS9. That's enough. But I would like to put two drives in it. It is a single 1.25 MHz processor. The seller said there were no trays for the hard drives. I am not sure how I will get those...maybe buy another junker. Kathi