Problems running a mixed stable/testing system

[Shawn Willden <shawn-deb@willden.org>]

My file/print/web/e-mail/everything server is running Woody, and I'd like to 
mostly keep it that way.  However, there are a few packages I'd like to pull 
from Sarge, and possibly even Sid.

I've read through the docs that say how to do this, and they make perfect 
sense, but the approach described doesn't seem to actually work.

As I understand it, I should be able to just add the appropriate lines to 
sources.list so that I have access to the newer packages.  That works, and 
apt-get and aptitutude both want to upgrade my system like crazy.  To prevent 
this, I should be able to just put the line:

Apt::Default-Release "woody";

in a file in /etc/apt/apt.conf.d (I put it in '71local').

But "apt-get upgrade" and "aptitude upgrade" (my preference) still want to 
upgrade my system like crazy.

So, I went the next step and put the following in /etc/apt/preferences:

Package: *
Pin: release v=3.0*,a=stable

But, *still* "apt-get upgrade" and "aptitude upgrade" want to upgrade some 
packages, though not many.  In fact, the packages it wants to upgrade are:

automake1.6
ethereal
ethereal-common
libfam0
libpng2
libssl0.9.6
openssl
python
python2.1 (Held back due to unsatisfied dependencies)
courier-imap-ssl (Held back due to unsatisfied dependencies)
courier-pop-ssl (Held back due to unsatisfied dependencies)
courier-ssl  (Held back due to unsatisfied dependencies)

But I would rather stick with the stable versions of all of these.  Actually, 
the only packages I want to pull from Sarge are a few that aren't in Woody at 
all.

So, questions:  Why doesn't setting the default release work like I expect it 
to?  And why does pinning the Woody packages still leave a few to get 
upgraded?  I've even tried setting the pin priority to 1001, which should 
force packages to *downgrade* to satisfy the pinning (not what I want, 
really, if I choose to explicitly upgrade a package, I don't want it 
downgraded again), but that doesn't change the behavior either.

Suggestions?  Am I missing something obvious?

Thanks,

Shawn.