TU2-ET100 (V3.0r) will work with Mac OS/X 10.5.  To install the TU2-ET100:

1. Connect the TU2-ET100 into an available USB port on your computer.
2. Drivers will install automatically.
3. “A new network interface has been detected” window appears.  Click “Network Preferences...”.
4. The “Network” window appears.  Verify “Configure” is set to “Using DHCP” and then click “apply”.
5. Plug an Ethernet cable from the TU2-ET100 to an available Ethernet port on your network.
6. Verify that the “100Mbps” and “Link” LEDs on the TU2-ET100 are lit green.
7. On the “Network” window, verify that “status” shows “connected”.  An IP Address, Subnet Mask and Router [address] should now appear.