I have a 2 computers on a network without any router , both running windows xp and both connected by the normal networking cable (dont know the name).I can share files from the laptop but when i try to share from the desktop pc it always says
"An error occured while sharing ... The server service has not started .The shared resource was not created at this time "Please help im very new to networking

The server service fails to start for some reason. Go to Administrative Tools->Services and try to start the server service manually. If it fails, read the error messages and also look in the Event Viewer.

You can only use a cross-over network cable to link two computers.

You have to use a hub or switch to link three computers.

You could also use a router, which has Ethernet ports.

See this page - http://www.legge40.freeserve.co.uk/Networking.htm

Eric,
http://www.legge40.freeserve.co.uk/BuyerBeware.htm