I have my main PC wired to the router. I have my notebook and netbook operating wireless as well as a wireless printer. I can access and use the printer fine from the wireless PCs. Is it possible to use the printer from the main PC with the main PC on an ethernet port of the router? I think it should. Any help?
It all depends.

What is the IP address of the printer? Can you ping that address from the cmd window on the wired in PC?
I am also assuming your wireless security is set up and that you can actually connect to the wired PC properly from the wireless devices?
Also...
Is your wired in PC running 32 bit or 64 bit windows?
This little known nasty is starting to bite a lot of folks! As for me, I have a wireless printer at home and have to share it from a 32bit XP PC as my printer vendor does not offer a 64bit Windows 7 driver!
My 64 bit Windows 7 laptop will simply not connect to the printer, even though it "sees" it over the network. The work-round was to have a 'share' set up on my 32 bit Windows/XP PC that acts as a printer 'router' if that makes sense?