Paste data into cell based on date variables

Hi there,
I have two spreadsheets, the first, lets call it 'Daily Totals', has cells in a column that contain data I want to copy then I want to paste that data into the other spreadsheet, lets call this one 'Downtime', based on a few conditions.
The corrosponding cell in column A of the cell in the Daily Totals sheet that contains the data I want contains a date. I want to use that date to look down Column A of the Downtime spreadsheet and find that date then go across to column E and paste value.
So, when looking down column A of Downtime to find a date, I would need excel to look down column Q in Daily Totals, find the last cell containing data greater than zero (there are also zero's and blanks in the column) then look across to column A to retrieve the date to look for. Once that is done it could then go across to column E and past the data I have copied.
It's quite hard to explain but I hope someone can understand it
Thanks in advance
tanewha