Here's how you can convert the week number into month in Excel 2003:

1. First, create a new column next to the column with the week numbers.
2. In the first cell of the new column, enter the following formula:
   Code:

   =DATE(A2,1,1)+((B2-1)*7)

   (Assuming that the year is in column A and the week number is in column B)
3. Press Enter to apply the formula to the cell.
4. The cell should now display a date value. Right-click on the cell and select "Format Cells".
5. In the "Number" tab, select "Custom" from the list on the left.
6. In the "Type" field, enter "MMMM" (without the quotes).
7. Click "OK" to apply the format to the cell.
8. Copy the formula down to the rest of the cells in the column.

This should convert the week numbers into the corresponding month names. The formula works by adding the number of weeks (minus one) to January 1st of the year, which gives the date of the first day of the week. The "MMMM" format code then displays the full name of the month.