Hi,
Please check out this wonderful posts while working with lookup
http://ronaldlemmen.blogspot.com/2006/12/filter-data-in-crm-lookup-field.html
http://social.microsoft.com/forums/en-US/crmdevelopment/thread/3f6c8c3d-73a7-4601-98a3-f72cc4c7ea9b/
http://crm.georged.id.au/post/2008/02/16/Filtering-lookup-data-in-CRM-4.aspx
http://crmintherealworld.blogspot.com/2009/02/creating-sub-lookup-in-microsoft-crm-40.html
http://jianwang.blogspot.com/2008/05/mysterious-crm-lookup-i.html
Bye…
