Charts - covering multiple workbooks

Hi,

Iv been pulling out all my hair with this one (even tho there wasnt much of it to begin with!)

I am currently doing a project for my work on excel creating spreadsheets of weekly targets and stats weekly. These figures are on multiple workbooks.

as example

W/c 25/06 will have stats of total sales for individuals weekly. Then w/c 2/07 stats would need to follow on the same chart from where the 25/06 finished off.

I could do a chart for the week but that would be pretty pathetic. What i need as the sales are located in many differnt workbook (not sheets) and im having problems creating a chart to cover 2 different workbooks (let alone 5 months worth)

How can I get round this? Putting all the data in one workbook is not a option.

Can Excel do what i need it to do?

Any help I would be grateful for.

Thanks

Bob