I'm trying to ditch the new intel driver due to problems with my external screen which are described here and I have not been able to resolve.

However, since the i810 driver is now a symlink to the intel one, I can't revert to it by just changing my xorg config. It certainly takes some fiddling but at least I can get it to work properly which I can't seem to do with the newer one.
Most distributions allow you to choose the older driver, but this doesn't seem to be the case with Debian.

My question is, how do I switch back to i810?

Thanks.

I would more suggest that you go to freedesktop mailing list and post your question. Did you do that already? Overthere are the developpers of this driver so they could try to help you and maybe based on your hardware they would make a patch. If they don't, then yeah revert.

Reverting:

What happens if you do this:
apt-get -t etch install xserver-xorg-video-i810
(you need an _etch_ or _stable_ line in /etc/apt/sources.list)

And in xorg.conf, put back i810.

Maybe removing the xserver-xorg-video-intel also could be usefull.

I also have a critical bug on this new driver (it freeze my machine). The patch is available but hasn't entered testing since months due to other bugs..

It worked!
I only had to uncomment the lenny repositories and add a stable one, as you suggested. Now I only have to keep the driver from updating.

Posting the intel problem in the freedesktop mailing list is a good idea.

Thanks .

I think by Apt-pinning or in aptitude there should something like freeze

Yep, your initial post in the other thread was clear, try to post something like this. Maybe it would also help me.