Sorry, should have mentioned how to do that. As far as I'm aware it's not installed with all versions of Excel but I know it's in 2000. To add it try this:-
Click View, Toolbars, Control Toolbox. Then click the More Controls button (the one which has a hammer and spanner icon). This will bring up a list of all the ActiveX controls available on your machine. Look for Microsoft Office Spreadsheet and click it. You can then 'draw' the control on a worksheet.
Once you get it you can the program it in all sorts of way, or you can enter directly on it. This is quite a big topic so if you've got any specific questions then post again.
Good luck!
D