History from SQL Agent Jobs (SQL Server 2005)
You need msdb.dbo.sysjobhistory and a few JOINs of course to read the data

To change how SQL Server Agent uses this table, use this stored procedure with suitable values

EXEC msdb.dbo.sp_set_sqlagent_properties
    @jobhistory_max_rows = 1000,
    @jobhistory_max_rows_per_job = 100