Saw this on Railroad Line:
Go here: http://www.incompetech.com/graphpaper/lite/
Set paper size to 8 1/2 x 11.
Set grid size to .35 CM (not IN)
Set number of squares to 120 x 160
Then hit the 'download' button, and you have a PDF file for 1' square HO scale grid paper...
By the way, printing this out is a good way to test how well your printer is in 'precision alignment'. You'll want to put a scale ruler on both vertical and horizontal dimensions to make sure the printer did print them exactly square all the way up and down the page.