I've had this problem ever since moving over to OS X and I'm confused as to whether this is an OS issue or a printer issue. Here it is: In OS 9, using my Epson 960, I would be able to print in Photoshop perfectly centered documents. The default setting was "centered" and when I printed something on one side, and then flipped the paper over, the other side would print out perfectly aligned with the previous side. But in OS X, I struggle to get centered documents. I have to override the print dialogue box by deselecting "center" and manually calculating what the correct margins should be, then compensating for the fact the margin settings never come out at their correct setting. My question: is this a printer issue (that is, printer software) or an OS issue?