Yes, I was using MYOB AccountEdge and had the same problem when trying to run it on an Intel Mac (my G5 was in the shop - needed a new power supply).
MoneyWorks itself doesn't do payroll. Their theory is why pay yearly updates for the part of the software that doesn't change? What most users of MoneyWorks (and other software that doesn't handle payroll) do is simply enter the deductions and such manually from tax tables.
But, what you can do with MoneyWorks, is set up a recurring transaction (a 'payroll' cheque for example) that occurs every pay period (that you specify). If nothing changes, simply post it. If anything changes, such as hours, deductions, vacation pay etc., you can change the amount in the recurring transaction to reflect this. Quite easy actually.
There are of course other programs, including online programs, that strictly do payroll. TD Canada Trust also has a service for doing payroll as I'm sure other banks do as well. But MoneyWorks should be able to handle everything else for you, without the need to purchase an upgrade every year.