Printer - did you upgrade the drivers to be compatible for XP SP2? If not
go to the printer manufacturer's web site and search for new drivers. They
may no longer support your printer for this SP - in that case you'll either
need to buy a new printer (one supported for WinXP SP2) or uninstall SP2 to
regain functionality of your printer.
My Computer - what error does it give you when you try? (My crystal ball is
in the shop and my ESP has been flakey lately, so I'm not getting a read on
your specific error).