You have to create a port for those printers using HP IP printing option.
You will still need drivers from the Manufacturers of the printers.
Snow Leopard removed AppleTalk which was a really easy way to access network printers.
Bonjour may work for you too.
I have just bought a Apple Mac Pro running Snow Leopard yet it does not print on any of the 3 printers connected to the network. The Mac sees the printer but there are no drivers for any of MY printers.
I have a HP 1020, Connon IP4600 and a Lexmark X324n XL all running of a Windows network.