darbax - I have the Proporta case and I highly recommend it - mainly because it offers absolutely rock solid screen protection thanks to the aluminium sheet in the cover.

I tend to keep the N800 naked when I am at home for easy access to the USB port, and put it in the Proporta case whenever I go out - when it is at risk of damage.

You can see a mini-review I wrote about it in my N800 blog if you are interested.