First you need to share the directories you want, try not to share the main root drive, if you do set a password for access, select the printer and in XP rightclick and select share on the network. you might have to load the driver onto the other printer.
When I didi it my other PC picked up the shared printer and installed it as it was a recognised driver in XP.
then try to print a test page.
look as click here for a lot of networking info