network issue

I can see other computers on my network, but I can't print.

Here's the setup.

1. The main PC is hooked up to the Cable modem.
2. The Modem is connected to a wireless router.
3. I have an IBM thinkpad that is also connecte to the wireless router.

and now the problem.....

4. My new MBP is also connected to the wireless router via Airport

What do I have to do to print from the Mac?

Someone please help. I'm still new to the Mac world.

Thanks