At home, both my iMac (20" core duo) and MacBook (black) connect to my WLAN. The machines have pretty similar specs (though the iMac has only 1GB while the Macbook has 2GB). Yet, when the two are placed side by side, with max WLAN reception, the MacBook finds and loads web pages about 5 times faster. The iMac feels almost like it's connect via a modem, instead of a 2000 DSL connection. With a wired connection to the router, the iMac is almost as fast a the macbook (via WLAN). These tests are conduction with only one machine connected to the WLAN at a time. Browser caches were cleared before all tests.
Anyone else find their iMac to be slow over airport. I notice this especially with web-page loading (e.g. where multiple accesses are required) rather than straigh "downloads" (though the MacBook still has a real edge).