2003: Creating HTML version of Excel sheet containing pivot table

Select cells containing pivot table.
File > Save as Web Page.
On Save As dialog:
- Save: "Selection: PivotTable"
- Check "Add interactivity"
- Click "Publish...":
-- Add interactivity with: PivotTable functionality

Note:
When the HTML is opened, the layout will always be the same (as the first time the excel file is saved-as HTML), user's changes while using it won't be retained.