Hmm, deja vu... Here goes again. Jabulani is right, if its got a USB port and doesn't have the apple logo plastered all over it.. don't bother. On the other hand if its connecting via ethernet, pretty much anything will work. Specifically the Gigabyte B49G and later routers are fine, as well as the 604 Dlink and the netgear 834gt. I use the netgear and gigabyte daily with a mac mini and have had iMac, eMac and powerbooks join the network with no problem. First time setup is dead easy.
Simply plug in the router and connect to your powerbook using a ethernet cable.
Go to system preferences, network, and select "built-in ethernet" from the "show" box, now click "configure".
On the TCP/IP tab select the "manual" option for "configure IPv4".
Now assign the powerbook an IP and submask in the same range as the default ip for the router. Usually the router will be something like IP "192.168.0.1 and submask "255.255.255.0" so make the powerbook IP " 192.168.0.199" and submask "255.255.255.0".
Click "apply now".
Launch safari and enter the ip address of the router in the address bar (192.168.0.1 in this example) and hit enter.
You should be presented with the router login screen. Login and configure the wireless access of the router.
The simple approach is to enable DHCP on the router and configure your network adapters accordingly i.e. set "configure IPv4" to "using DHCP" in the TCP/IP tab in the network setting of the adapter.
When first setting up your router, don't bother with any security settings, first make sure that the hardware is working and connecting and then you can do the security when you know everything is working fine. Its a good idea not to be connected to the internet during this test period.
OK so you've setup DHCP and given the router an SSID (don't turn off broadcast SSID yet). Use the options for an open network with no security.
Now reboot the router after saving the settings. They usually do this automatically.
Go to the network settings in system preferences and select the airport adapter, set the TCP/IP to get an address via DHCP and apply. When you go to the airport tab the SSID of your should appear in the network list. If it doesn't, click new network (the +) and it should be detected. You should now be able to join the wireless network.
You can check the status of the network connections by choosing "Network status" in the "show" box. OS-X will tell you which adapters are active and which one it is using for internet, usually the fastest one.
Unplug the ethernet cable and you should see the internet connection migrate to the wireless adapter. Thats it... you can now configure security to your hearts desire.
Most routers want you to do admin over an ethernet connection, but I've not had problems doing it over the wifi, but remember that your logins are sent in the clear.
Hmm... hope this is what you were after. In terms of rankings for the routers, I find the gui interface on the netgear better than the gigabyte and the dlink. The range on the netgear is better than the gigabyte and about the same as the dlink. The gigabyte and dlink have slightly better signal stability. Your milage may vary.
Good luck with your selection.