As far as I know IT IS NOT LEGAL to distribute parts of Microsoft Office along with either commercial or not-commercial programms.

If you need to have graphs, and not to depend on Microsoft (and to cheat your customers to buy MS Office (if they donot have it), you should look for a third-party graph tool, or to create your own)

Check following articles & links:

1.'Make a light chart control'
http://www.vbsquare.com/articles/graph/index.html

2.'...82 Programs listed in ActiveX Controls'
http://www.bhs.com/downloads/category.asp?cid=16

3.'The Microsoft OLE Chart Object'
http://www.vb123.com/toolshed/99_graphs/msolechart.htm
(It says: 'The important point to remember is that the OLE objects need to be pre-installed on the computers where you want to run the software.')

I'm not sure that this will help you...
But it is a starting point (i think)
Best Regards