The company I work for used to sell Pegasus Opera. Yes, accounting software is usually very old and there is a LOT of messing around when things go wrong, usually manual modification of the underlying databases.

That said, for SME's the time saving aspects can be massive - I know of one company who used to manually calculate all the payroll stuff and it took one person all day every week. After that it took about 1/2hr.

Gareth