Multiple xyplot on a page

Dear all;

	I have a set of 5 xyplots each with 8 panels and wish to place 2 on
a letter-sized page. I tried using pdf() to specify paper size and plot

size:

pdf(file = "fig1b.pdf", paper = "letter", onefile = FALSE, width = 5,

height = 5,
 family="Helvetica")

par(mfrow=c(1,2))

but it did not work. Any suggestions for placing mutiple xyplots to a page?

TIA,

Richard