if there any field like id....which is sequentially increasing....or any autoid field in table like1,2,3,4... then do following.....
1.On insert coding check row count
2.If row count is 200.
3.Execute to command one is to transfer record from one table to secound which is selected by order by id asc
4.Delete from first table
5.Refresh gridview...rebind to database...
int RecordsCount = Gridview1.Rows.Count ;
if (RecordsCount == 200)
//execute folowing command
cmd=new SqlCommand("insert into ArchievedTable(col_a, col_b)
select top 50 col1, col2 from RecordsTable
order by id asc",con);
cmd1=new SqlCommand("DELETE FROM RecordsTable WHERE id IN (SELECT TOP 50 id FROM RecordsTable ORDER BY id asc)",con);
//then call gridbinding code here i.e refresh grid
something like this....hope it will help....