|You have to configure the routers wireless option if not already done.|
Then you have to configure the Windows 2000 wireless card to use the appropriate wireless network, which should be shown in the available wireless networks list.
You also need to configure the encryption key, if you use wireless encryption on the router.
And it is strongly adviced to use wireless encryption.
This all has nothing to do with the configuration on the Vista PC, except it's also connected via wireless.
But you can configure your wireless router from the Vista PC by using a browser.