C# - Comparing Data From A DataGridView Control To A Constantly Updated DataTable?

I have a DataTable that's constantly being updated with new data from my database via a timer. That data is eventually reformatted and displayed in a DataGridView control.In an effort to prevent the DataGridView from completely refreshing from re-databinding (thus, clearing out selections, resetting scrollbars, defaulting sorting settings, and making the gridview flash as it reupdates), I'm simply removing old rows from the datagrid that no longer exist in the DataTable, and adding new rows to the datagrid that appear in the DataTable since the last update.

For the sake of simplicity, we'll call DataGridView the LEFT table, and DataTable the RIGHT table I'm looking for a way to go through both tables (LEFT and RIGHT), and remove old rows that are no longer in RIGHT and delete them from LEFT. And look for new items in RIGHT and add them to LEFT. Each table has a column called "RecID" containing a unique id for each entry that can be used for comparison. is there a way to do this all in one loop? What I'm looking for, in pseudo code:

<loop through everything>
if RecID does not exist in LEFT but exists in RIGHT
add new item to LEFT
if RecID does exist in LEFT but does not exist in RIGHT

[code]....