WHERE stmt with Date

Odd situation. A new site has an events-by-date page. The data has a start-date and an end-date field (aside from the auto-publish special fields).

When trying to query the data for:

'where' => "end >=NOW()",

The events that would be currently happening don't show up.

If I set up up as:

'where' => "end >=(NOW() - INTERVAL 8 HOUR)",

It works perfectly. This creates an 8hr widow, but I would have thought the first option would work.

I'm obviously misunderstanding something here. Can anyone clarify this for me please?

Thanks!