We have found one software suitable in our database for this conversion.
Documents saved as .sdw files were originally saved in old StarOffice or in early version of it's successor OpenOffice.org. Most open source word processors should still support this format and open it, however exporting it to an Excel spreadsheet (.xls, .xlsx) directly may be a little problematic.
Your best course of action would be to open the .sdw file in any word processor that allows it and manually copy and paste the bits you want to Excel so you can save it as .xls file.
SDW
Files with sdw file extension can be most often encountered as text documents from StarOffice and some versions of OpenOffice.org.
XLS
Files with xls extension are best known as spreadsheets from Microsoft Excel. A spreadsheet is basically a grid of cells sorted in rows and columns. Each cell can contain text, numeric or formula data. Excel XLS spreadsheets can be opened in most other similar programs, such as OpenOffice.org Calc.