Eh, just wonder why the equal operator can make the execution plan shows that the index was used.

declare @todaydate datetime

set @todaydate = getdate()

select * from tbl

where col = @todaydate

However the execution plan shows that the index wasn't used in <, <>, >, >=, <=?

declare @todaydate datetime

set @todaydate = getdate()

select * from tbl

where col > @todaydate