In essence, you would like to print "borderless." Most printers require that the print be within a specified region on the paper, with margins on each side — often with one margin being greater than the others (typically the bottom). You can find out what these margins are from within Photoshop using Page Setup. (The location of Page Setup may vary from version to version, but in CS and CS2 it can be accessed from either the File menu or Print with Preview.)
As an alternative, some printers have a special mode that allows printing right out to the paper edge. To do this accurately would be almost impossible in most printers, because the paper would have to be perfectly aligned, which isn’t going to happen, or you will overprint some borders and have white lines along others. So the printer makers have typically provided a "borderless" mode that actually enlarges the print by a few percent in all directions, so it goes over the edge of the paper in all directions, leaving no margins. You have to select this from the printer driver, either by default or per photoshop session. To set the HP 7550 to do this by default, follow the instructions here <
http://h10025.www1.hp.com/ewfrf/wc/document?lc=en&lang=e n&cc=us&product=72891&dlc=en&docname=bpy2104 9>. To do it within Photoshop for a given session, select Page Setup (as described above), select the appropriate printer, and access its settings or preferences and then follow the steps in the foregoing link starting with number 4.
