Try Mailings | Labels | Label Options. With Microsoft selected as the label
vendor, scroll down to the Index Card selection. Two of them are 3"x5"
(portrait and landscape).
This is one of the most important improvements in Word 2007, to my mind.
Microsoft has created generic "label" layouts not only for the most common
types of letters and 2-up or 4-up cards but also, in effect, document
templates for a wide variety of paper sizes (including the much-requested
"compliments slips"). Back in the Labels dialog, you can click New Document
and get a page of the desired size.
One caveat: the page is set up as a table cell. Very likely you won't want
this. But you can select the table handle and press Backspace to delete the
table and leave a single page with a single empty paragraph. You'll need to
change the margins, which are currently set to 0" all around.
Whether your printer will actually handle this better than if you set it up
manually as a custom size (which is how Word still views it), I don't know.
