Hi Logo,
you can set the DataGrid colwidth Property at Design-time by:-
Selecting the DataGrid control on the form and right-clicking the mouse. Select Properties then the Layout tab.
I don't think you can change the column width at Run-time.
Thats another reason to use the MSFlexiGrid control instead of the DataGrid control because it does allow Run-time manipulation of the Colwidths. You would use code as suggested by TheMasterFly in order to achieve this.
Regards,
Codefish