Automating .ics import from Mail to iCal

I've got a setup that will take all the events in a range of dates in Outlook 2007 (at work), create an .ics file for it, and email it to my home email address. The email comes with a few .gif files as well for prettiness.

Is there a straightforward, relatively failproof way to automatically take the .ics attachemnt when it is received in Mail.app and import it into a specific iCal calendar? The calendar I'd like to use is the default calendar that pops up in the dialog box.

I've done some mucking about with Automator – it sort of works, except that sometimes it 'finds' the .ics file multiple times, and so tries to import it multiple times… if it only finds the file once, it works fine.

EDIT Jan-19 – The "Add to iCal Automatically" solution in Mail.app's preferneces is better than what I had, but still not quite enough.
1. I don't see that it allows me to specify what calendar it's adding the event(s) to.
2. It's not automatic – I would need to open the email to do it. My intention is for an unattended workflow.
3. It's too broad – I only want .ics files that meet certain criteria (ie, only in emails from my work email address), not every invitation that I receive.