Yes. If you are using XP it is easy. Follow the networking set up wizard if you haven't already got the network going.This sets up windows to allow sharing etc.
In the control panel you can select the printer properties and set it as shared (it will be avialable as long as it is connected to a PC which is on).File sharing is simple - select the files/folders you want to share (right click for options) - set them up as shared and create somewhere in 'my network places' to keep them - then each PC will have access to them. You can then choose edit permissions etc to stop your family etc deleting/editing your files. Follow the windows help topics.