I'm having trouble with ArcGIS 10 not overwriting tables in personal geodatabases (*.mdb). I have the 'overwrite outputs of geoprocessing operations' box checked.
Instead of simply overwriting a table with the new output, it annoyingly appends a "_1" at the end of the name. I can't find info anywhere that states you must delete the old tables before running a process. Maybe this is an issue with personal gdb's compared to file gdb's. I haven't had this problem with file gdb's.