Retrieving last record in each group from database - SQL Server 2005/2008

;with cteRowNumber as (
    select COMPUTERNAME, SERIALNUMBER, USERNAME, LASTIP, LASTUPDATE, SOURCE,
           row_number() over(partition by COMPUTERNAME order by LASTUPDATE desc) as RowNum
        from YourTable)
select COMPUTERNAME, SERIALNUMBER, USERNAME, LASTIP, LASTUPDATE, SOURCE
    from cteRowNumber
    where RowNum = 1

http://stackoverflow.com/questions/4751913/retrieving-last-record-in-each-group-from-database-sql-server-2005-2008