It depends....on how much experience you have and what type of system you are using now. Not considering those two factors, I would suggest using a CPA for the first year you do your payroll, this willl get you started off correctly and make sure that you do the proper reporting and payment of taxes. (Be sure you establish a seperate payroll account--no exceptions!)
After the first year, strike out on your own doing payroll, either use the same program that the CPA uses, or I suggest Quicken Payroll, the in-house version. However, the on-line verision will also help eliminate some problems also.
Other factors to consider, how much time wil you have to devote to payroll each week, and how computer literate you really are.