The easiest way to add a Code 128 bar code to an Excel spreadsheet
would be to use a bar code ActiveX control. Code 128 bar codes are
much more complex than Code 39 bar codes therefore it is very
difficult to use a bar code font to produce Code 128 bar codes. In
addition bar code fonts produce very porr quality bar codes whereas a
ActiveX control can produce a very high resolution image that will
scan perfectly no matter what printer you print to.
The best bar code ActiveX control on the market is the TAL Bar Code
ActiveX control. You can download a demo from the following URL:
http://www.taltech.com/products/activex_barcodes.html
The demo version of the control comes with a sample Excel spreadsheet
that demonstrates how to use it in Excel.