Standard client server accounting packages normally have fairly comprehensive Payroll modules that integrate with General Ledger and Job Costing.

Payroll modules often mimic check books and often even look like a check book on the screen.

The purpose of integrating Payroll with General Ledger and it so that one can see the general health of the company by way of looking at debits and credits.

Integrating Payroll with Job Costing enables one to see what is spent vs. what is paid on different jobs.