There are several ways to link home PCs.
Check out www.homepna.org
If you have phone jacks near both PCs, all you need is a pair of PNA type network cards.
Other options in order of expense / work:
Wired networking with CAT 5 wiring and network cards along with a switch / hub
(You may be able to get by with just a cross-over style network cable running between the 2 PCs)
Wireless networking.
I am concerned about security with wireless networks though.
If you have easy accessto the walls in both rooms, I would run the CAT5 cable, and install a switch or hub to link the 2 PCs.
Properly done, this can add value to your home.
If running cable is a problem, my first choice would be the home PNA setup.
After you setupyour network connections, you need to install network protocols on both PCs.
Either TCP/IP or NetBUI are needed.
Then, you need to enable file and printer sharing on the PC with the printer connected to it.
Here are a few links for further information:
http://www.practicallynetworked.com/
http://www.wown.com/
http://compnetworking.about.com/cs/basicnetworking/
Chas