A very nice tool that tackles the problem is Remote Calendars, which is a COM plugin for Outlook to connect to iCalendars all over the internet, and perform a periodical synchronization between both. The tool is straightforward to install and use, and has all the features I was looking for:
- One-way synchronization from Google Calendar to Outlook; two-way is also possible but I didn't want that ;).
- Automatic categorizing of imported calendar events; optionally mark these events private.
- All settings like "all day event" or "recurring" are copied from the Google Calendar.
In short: the tool does exactly what it needs to do. The only disadvantage in my opinion is that you see a small "iCalendar update" window appear every now and then, which seems to freeze for a moment when no internet connection is available. Besides that, great tool, check it out!