Printing from three computers?

I have a desktop PC that is running Windows XP and then I have two laptops that are running Windows Vista. I would like to plug the printer into the desktop machine and then be able to print from desktop and the two laptops. What is the best way to do this so that I do not have to keep physically plugging the printer into each laptop? All three computers are using the same wireless router to connect to the internet. Also, if anyone out there knows, could you point me in the direction of how to set up a folder that all three computers could see and share files? Thanks for all the help guys!

 

Share the printer on the XP machine.

Create a new folder and then share it.