Greg
I'm very confused!!
"I'm really trying to get the 2007 monthly sales numbers to update
automatically
according to the date in 2008" Surely the 2007 monthly sales numbers are
what they are - How can 2008 change last year's sales numbers?
"In May, I want the weekly sales for 2007, to update according to the
numbers I put in for 2008" - again bearing in mind days of the week will be
two days adrift (Mon 7th May 2007 and Mon 5th May 2008) explain how you want
last year's figures to update!
"I just have all the month totals for 2007, and zeros for the future months
of 2008"
What do you want instead of zeros for the future? (It would be nice if Excel
could forcast the future)

"Greg" wrote:

I'm trying to compare sales from 2007 vs 2008 with a percentage change. I'm
really trying to get the 2007 monthly sales numbers to update automatically
according to the date in 2008. In May, I want the weekly sales for 2007, to
update according to the numbers I put in for 2008 to have an accurate weekly
comparison. Right now, I just have all the month totals for 2007, and zeros
for the future months of 2008. Any ideas?