Modifying Value in DataGridTextBoxColumn in DataGrid

hi all,

I have a one datagrid on my Form, this is my Sale form.

i have attached this datagrid with programmatically created Dataset. that have one data table with following field...

ItemId, ItemName, ItemUnit, etc...

well, i want that when i type in datacolumn called "ItemName" the corresponding list of Item will coming and user can select one of the item from it and automatically the itemunit and other related para will be automatically set in the currentRow..

Can Anybody Suggest for the same.. \

Thanx,

Tejas Kishanwala