A couple of things to consider.
First, can you connect to folder shares on the computer with the printer
from the one that can not print? If they can't then that's a problem to
solve because being able to connect to shares is a prerequisite to being
able to print. If the user can connect to shares, but not connect to the
printer, then that reduces the scope of the problem and it will be easier to
solve the problem.
What make and model of printer is it?
What exactly is the symptom (e.g. access denied, "unable to connect")?
"Print Servers" come in a variety of forms. For example, you can get
relatively cheap "print server" boxes that are little more than a LAN
(Ethernet adapter) and parallel port. Using one of those, any of your
computers could print directly to the printer through such a box. This will
eliminate the 10 connection limit on the XP Pro workstations.
Some "Print servers" emulate a Windows Print Server so you can connect to
the printer on one of those the same way you would to the computer with the
printer now. Other "Print Servers" don't have this capability, but you can
easily print to them using a "Standard TCP/IP port" (created via the Add
Printer Wizard). Still other ones come with their own software that will
create a different type of "port" that automatically discovers the "print
server".
Any one of these will be a much cheaper and probably perfectly adequate
solution for 8 users than purchasing a computer and Windows Server.