Mac OX X 10.6.8 running Synergy 1.3.7 (server) Windows XP SP3 running Synergy 1.3.7 (client)
Mouse functions work fine. The arrow keys and function keys on the mac get sent to the XP client fine. The only problem is I can't get the letter keys to work. I've tried running 1.4.3 beta on both sides as well, with the same result.
When running in DEBUG1 mode, I get the following output when pressing the letter keys while the mouse is focused on the XP machine: