Linda,
>I am using mmDataGrid, just because that's the first thing I came to on the tool bar.
Gotcha...you should actually be using mmGridView...mmDataGrid is simply there for backward compatibility with ASP.NET 1.x.
It sounds like you're trying to provide incremental search for a web grid? You may have problems getting the default ASP.NET GridView to function the way you describe. But to answer your question about locating a specific row in a DataSet, you can use a DataTable's Rows.Find() method to locate a row by primary key. You can use the DataTable's Select() method to search for rows by a particular filter expressions.
Best Regards,
Kevin McNeish
Eight-Time .NET MVP
VFP and iOS Author, Speaker & Trainer
Oak Leaf Enterprises, Inc.
Chief Architect, MM Framework
http://www.oakleafsd.com