Yes!
The JetDirect card IS actually a print server.
The printer will either have a DHCP supplied IP address from the 3Com, or a fixed IP address. You should know which, as you set it up!
The easiest thing to do is to print direct to the IP address.
First, find out the printer's IP address - do this by printing the configuration page(s) of the printer.
Next, Add a Printer to each wifi PC - Use the Wizard and select Local Printer (ensure that automatically detect is OFF), then Create a New Port, type is Standard TCP/IP. Now enter the IP address of the printer (ensure that the printer is ON) - you can accept the default port name. Now add the Printer driver - the HP LJ 5 is installed with XP by default, so you won't need any setup files.
That's it.
SD