Hi Scott, I've been running a somewhat complex system which uses an old PC as the controller for several years now and it works just fine. You can see pictures and details at:
http://www.ka7btv.com/cora.htm <http://www.ka7btv.com/cora.htm> This system deos not use the Echostation software to which you refer, but I see no reason why that shouldn't work fine for you. The system here does use Windows XP Professional, and it easily runs both Echolink and the custom repeater control program. Windows XP is the only operating system which I have found that correctly handles multiple sound cards. Good luck and please let us know of your progress. - Darrell/KA7BTV
