You might have a look at these links also...
Hardware recommendations to build a cheap ESX server - http://www.vmweekly.com/articles/hardware_recommendations_to_build_cheap_esx_server/1/
White box/Home ESX system - http://www.vmware.com/community/thread.jspa?messageID=620124򗙜
ESX on non-supported hardware to learn with - http://www.vmware.com/community/thread.jspa?threadID=77560
Community supported hardware/software for Vmware Infrastructure - http://www.vmware.com/vmtn/resources/communitysupport/