Yes, there is a custom format that you can use to show the number with 100 separators instead of 1000 separators in Excel 2003. Here are the steps to do it:

1. Select the cell or range of cells that you want to format.
2. Right-click on the selection and choose "Format Cells" from the context menu.
3. In the "Format Cells" dialog box, click on the "Custom" category.
4. In the "Type" field, enter the following custom format: #,##,##0.00
5. Click on the "OK" button to apply the format to the selected cells.

Now, the number in the cell will be displayed with 100 separators instead of 1000 separators. For example, if the cell contains the number 120000.00, it will be displayed as 1,20,000.00 after applying the custom format.