to network them together, you have to have identical accounts on both computers. Printers can be shared in different ways.
I have three Laptops that share internet and I have a print server for my printer. I installed the drivers into each laptop for the printer. This way, no other computer has to be one to print.
Since yo said it was a small business, you could probably get someone to help you with this, since it would be a business expense.
I Work in a small business with 2 pc's that already share a wireless internet connection. We would like them to share printers and files also. Both run Win XP SP2 both are Dell one is a Dimension 2400 the other is a Dimension 5150.