Query DateTime DataType For Current Or Future Events

I have a sql server express 2005 database with a table named Events with a column named Date (datetime datatype).  I want a query that will display all rows that are either current or future but not past.  I suspect there is a simple way of doing this.  As a Newbie searching archived threads this is what I have come up with so far.  I determine the number of days from present:
SELECT DATEDIFF(day, Date, GETDATE()) AS NumberOfDays
FROM Events
This yields number of days from present with positive numbers in the past and negative numbers in the future.  Thus setting a WHERE clause to <= 0 would limit my results to present or future events.  Something like this:
SELECT *
FROM Events
Where DATEDIFF(day, Date, GETDATE()) AS NumberOfDays <= 0
The error message states: "Incorrect syntax near the keyword 'AS'"
This feels like a clumsy way to approach this problem, but I have to start where I am.
Any suggestions on how to proceed will be greatly appreciated.