I'm trying to use WinRunner for automation and understood that TestDirector is needed for distributed Client-Server testing.

I would want to know exactly this is done ( It would be good enough for a big picture..)I came to know about TDAPI, Open Test Architecture API, etc..

More specifically I would like to know(for any client server product), how easy is it for automation with WinRunner and TD, compared to SilkTest.

thanks in advance,