Next thought is a hardware option, buy a network (RJ45/Wireless) to usb adapter and try that. One advantage to that is the host pc wont need to be on to print from the remote laptops.
We have successfully used the SEH PS03a on our home network for a while. The UTN connection gives full two way connection with our two printers. Be aware some ethernet print servers don't do the two way bit so although you can print through them, they don't send data back to the PC like error messages, or in the case of multifunction printers the scanner doesn't link. Check carefully that your printer is supported by the print server you choose and all the functions you want are available over the network or you could be buying a door stop!