He didn't mean a list of ALL spells, he meant a list where he can keep track of what spells his mage CURRENTLY has in his spellbook.
I've always found it VERY annoying when buying spells, that I couldn't easily see which spells he already had in his book, and which he hadn't yet.
For all I care, if he knows the spell already, give it a green frame with the merchant! That immediatly makes clear what you need to buy, and what not.
And what's the appropriate URL to that message board? I guess I can find it by going to the Interplay main site ... but if you know, you could just as well write it down here. Yes, I'm lazy.