Between deleting older things and renaming files as designers changed stores, I have no idea. I think I'd need a list of the original designers and first products to jog my memory. I know one of the oldest is the first Quarterly Assortment.
ETA: Okay, I stole the idea of going to the store account history. My earliest order was 4/06, and it was for:
Sweet Jane Stitches by Sandra Boddington
Playful Plaques by MandaBean
Quarterly Assortments vol. 1 & 2
My next order was a month or so later, and I got a few Mindy Terasawa kits (First Blossoms, Courage and Strength, and Playful--I forgot she used to sell here!) and Christy Lyle's Tag Book Treasures. I think everything from this second order is still on my HD.