I have configured Etch "Netinst" more than I can count on a vanilla PC but now I am ordering a SATA RAID PCI card. I am wondering how to set up RAID using a "hardware" RAID PCI card. Do I set up the RAID1 before I even boot from disk? I normally get to the partitioning section and just create one large partition but this is on one physical disk only. Now I have 2 physical disks that I want Debian to see as one (/dev/sda1). Am I correct in assuming that the disks are stripped before I even boot from the Debian disk or do I still need to do something via the partitioner.

Thanks for any pointers or assistance.

Yes during boot before you reach the OS stage you'll be greeted with the RAID card's screen.
Typically that screen will prompt you to press <F8> or whatever to configure your array.
Now if you setup a RAID-1 array there then virtually everything after that stage will see only 1 HD.

For whether Linux will see 1 or 2 disks...
Well, it actually depends whether your RAID card is truly a "hardware RAID" card.
If it is then congrats you got a single disk ~

Now if that's a "software RAID" or the so-called "hardware-assisted RAID" the story is really not quite predictable.
I'm sure if any such RAID card is supported by Linux at all...
I've had experience with an on-board nVidia RAID chip, but its actually a "hardware-assisted RAID" and requires a driver in Windows in order to function.
And when I install Debian on that box, it saw 2 disks, the physical ones. So the so-called RAID chip was in fact useless .