Hmm... I could tell you the answers for a sneak preview

Seriously though...
That was the theory, although I've never tested to see whether /dev/hda2 and /dev/hdc2 get wiped during an upgrade.

However, even assuming that they don't, certain other things will;
/bin/rop
/bin/rwp
The entries in /etc/fstab.
The mountpoints /programs0/ and /programs1/

(The mountpoints are what you 'see', and live on the root parition, that will have be wiped)

The easiest way to recreate these is to use the mkprgpt.sh script. If there is still data on /dev/hda2 (the partition formerly known as /programs0) then it won't touch it.
If not, then it'll at least get us started in the right direction, although the resulting /programs0/preinit.d/ startup script entries will need looking at to suit your set up.