Excel 2003

I have one spreadsheet called "Rate Matrix" which contains 5 workbooks
(GroupA, GroupB, GroupC, GroupD and GroupE), each of which contains a rate
table. The tables all have 12 rows, but varying numbers of columns. Heading

In my other spreadsheet called "Rate Calculator" which has 2 workbooks
(Calculator and Rates).

In the "Calculator" spreadsheet you enter the Rate Group in cell D4.

I want to put in to the "Rates" spreadsheet all the data from the
corresponding workbook in the Rate Matrix file. E.g. if rate group = A, then
copy workbook GroupA from Rate Matrix to "Rates" workbook.

Any ideas would be appreciated