hifo,
You have a wireless router hooked up to your DSL modem?

Is your PC connected to the router via ethernet cable, or is it connected wirelessly?

What model router?
and more importantly, give up some information about the Mac. So far, all I know is you have an Apple product.

Model?

Operating system?

is a Wireless card installed? (if you answer the first two, I can tell you how to find this one.

Does the wireless router have ethernet ports?

Does the Mac?

Is your router password protected?

How far from the router is the Mac?

You might not have to buy anything, but I can't say without more info

Lampie