Sharing a printer

[buzzbee]

Okay, I've got my cable broadband service now. I connected through a wireless roter then into the cable modem. I set up two computers to shere the internet connection. That all works fine. The router and printer are on the downstairs computer. Upstairs computer can  see the downstairs computer and both are listed im "my network places".
When i am upstairs I double click the icon for the downstairs computer and it says i cannot access that computer. What am I doing wrong?
Thanks
P.s. I tunred on file sharing and printer sharing in windows xp media center edition.

[Hi-Tech]

Create a user account on the PC with the printer for the PC that is trying to connect. That will giver you permissions on the PC you are connecting to. Also make sure both PCs are in the same workgroup...

[buzzbee]

I'll try that. Thanks for the help Hi tech