In order for your printer to directly receive jobs "wirelessly" it usually has to have the proper innards for wireless networking built in. Few off-the-shelf printers will be equipped for it.
You can also get a mini "server" that plugs into the conventional printer port, that receives the network input and passes it on to the printer; but typically these little jobs are about expensive as just getting another printer, and sometimes more expensive than the printer.
The "conventional" method, assuming your laptop can talk to another computer on your wireless network, is just to plug the printer into another computer using the common serial/parallel/USB/firewire sockets, and "share" the printer from that computer.
Any computer on your network, that has a printer attached, should be able to share that printer with any other computer that can connect on the same network to the computer that's connected directly to the printer.
With WinXP, all that's needed in some cases is to right click on the printer (Start|Settings|Printers and Faxes, right-click the printer you want, select Properties and then the "sharing" tab. In other cases (with recent security patches) you'll need to run the "network setup wizard" on the machine that "owns" the printer, and during network setup, select the "share printers" option.
In either case, you will need to install the printer driver on each machine that's going to use a given printer. You'll need to go back to the Start|Settings|Printers and Faxes and do an "add printer" on the laptop, for the laptop to be able to use a printer connected to a desktop on your network.