Elan Home systems: http://www.elanhomesystems.com/

GE-Smart: http://www.ge-smart.com/

Vantage: http://www.vantageinc.com/

Crestron: http://www.crestron.com/default2.asp

are a few of the higher end solutions.

For something considerably less expensive, have a look at :
http://www.gadgethome.com/cgi-local...auto.html?E+scstore+goto_home_automation