I have an issue which might be unusual but I can't find a decent description to help me find a solution. I am trying to set up a worksheet that I can easily update without having to manually pull all of the data every time. I have set up a worksheet that references a drop down box, pulls 100 data items from a Pivot Table, and then uses a combination of IF formulas and VLOOKUPS to fill all of the data in. This sheet works perfectly because it is a defined number of items so I just have the formulas filled to 100 lines. It's not particularly clean, but it works perfectly without VBA (which I'm terrible at).

The sheet that I'm trying to setup is not a set number of items. I am unable to post the sheet due to what it contains, but for example:

I have a sheet which contains all of the accounts that have purchased over a given time period.
This sheet contains the purchasing data for the past 24 months. I have also run a pivot table identifying all clients that have 0 purchases for the current month.
On a new sheet, I would like to be able to setup a drop down list with each region of the country (1 pivot table for each one), and when someone selects a region to review, it will populate all of the clients that have not purchased by their unique number. Ideally it would populate the numbers all the way down and then I could use VLOOKUP formulas to pull an additional data required, but I don't know how to make those formulas fill down matching the data pulled based on the region.

I honestly don't know if this whole setup is even possible. My workbook has already become quite large so I'm trying to avoid as much slow down as possible, but I don't know if I can make it work. Any help at all would be hugely appreciated!

NOTE: I am currently working in 2007 but I would prefer compatability with 2003 as that is the more common version in use for my target group.