Select Rows By One For Each Value

Tell me please how to select from a table only rows with different value of one of fields (n_pr field). But I need also to select some other fields where the values can be different for one n_pr field's value and select only first value of them. For getting list of n_pr field's values I can use derived table of query with DISTINCT operator but I don't know how to join with other fields of the table to get only one row for each value of joinning field n_pr. I am using SQL Server 2000 and this DBMS can use TOP operator to select only one row but all the ways I've tryed affect all the query and I get one row at all instead of one for each n_pr field's value. Also I need in this query to connect one more table. So for efficiency it better to do it in one query or in one stored procedure that return a recodset as it needs.