I don't know the model #s, size or age of your Maxtor and WD drives but can tell you that I've never seen a specific jumper standard shared by all drive manufacturers or even between product lines from the same manufacturer. Since you mentioned using a HD with a CD ROM, I can tell you that this can often through a real monkey wrench into the works. Be careful of "Master" settings. Some will allow that setting if only one drive is installed and some consider that the master jumper position means that a slave exists and you cannot use it with a single HD. What you need is the instructions from the manufacturer for each drive model to figure out their scheme. Unfortunately the only experiences I've ever had with Maxtor drives have been bad so I avoid them. I also avoid trying to mix drives from other manufacturers or even vintages. If one is older IDE and one is called an EIDE, ultra ATA, etc., I wouldn't mix them on the same cable. Maybe if you know the HD model #s that might help dig up better information about what jumper settings are valid.