That is a great question right, hard to tell when we don't know what we don't know. :-)
Of course, you will want to make sure all the employee information is correct, you would need to verify all the employee card windows, taxes, pay codes, deductions, benefits, etc.
Make sure tax tables are updated.
Since it is still really pretty recent, it is not like you want to "clear" data on the company either as most of the information may still be there.
I'm not sure how much turnover they have had, but do you flag all the employees to something, so then you know as you updated them which ones you have verified, etc. Or is a lot of it they want to use the same, etc.
Then do a trial payroll and see how well it will match up to what you are running now.
Of course I LOVE to hear this the more we have on payroll, the happier I am, yeah!
Thanks
Terry Heley
Microsoft