I recently tried printing a small piece (5.5*8.5) on an inkjet printer. It would print out way off centered. I encountered a similar problem to that when I had been using a laser printer and small paper sizes.
I order to get the piece to actually print in the right spot (bottom & Centered) I had to tell PM that I was using paper that was 7.5 * 8.5
I haven't encountered that problem outside of PM but I was hoping for a more elegant solution.
OS Win XP SP2 - latest printer drivers.
THe only thing I can offer as a commonality for both of the printers (LASER & InkJet - different manufacturers) is that the paper feed path is on the extreme right hand side rather than like old AppleLaserwriter/Laserjet that had a centre feed mechanism.