Prevent iCal from sending meeting acceptance email

If I received a meeting invite via Mail (usually atached as meeting.ics), I can open it with iCal and the meeting will be added automatically to iCal.

However, the meeting is "greyed" out until I click "Accept". This will automatically open Mail and send an email to the meeting organizer saying "Yes, I accept the invitation".

I do NOT want iCal to send meeting acceptance email. Is there anyway I can prevent this?

In my work Outlook (Windows XP), when I click the same meeting invite, a pop-up box will show up asking if I want to send an email and I can click "NO".

The reason I don't want to send meeting acceptance email is because it'll create a spam whereby tons of emails get send out to the meeting originator.