If you've ever wondered why “select 2/3” returns zero, here are two discussions that get into the reasons why:
http://www.windowsitpro.com/sqlserver/forums/messageview.cfm?catid=1690&threadid=128167&STARTPAGE=1
BTW, “select cast(2 as dec (18,8))/cast(3 as dec (18,8)) “ will return the 'correct' result.