I suspect that you are not using Windows Live OneCare.
If so, you're off topic for this forum, which is dedicated to Windows Live OneCare. You may want to try the Microsoft Public newsgroups here: http://www.microsoft.com/communities/newsgroups/list/en-us/default.aspx
If you are using Windows Live OneCare, the printer sharing feature only works with computers on your local network. You cannot share a remote printer or print to one.
Whatever method you are using to remotely access the office PC would need to support remote printing. If you are using a VPN solution, it may not be a supported scenario.
-steve
Microsoft MVP Windows Live / Windows Live OneCare, Live Mesh, & MS Security Essentials Forums Moderator