I didn't realize that anyone had popped up here.
Trufax: I completely concede that Toughness isn't an optimal choice for a caster, but it's not a completely illegitimate one--or shouldn't be, I believe.
A feat that is in the PHB shouldn't be a feat a player character isn't meant to take. If you're going to contend that it's actually for creatures, then it should really probably be in the DMG or a MM. In the PHB? That's a trap, and it's poor system design. Rewarding system mastery is nice, and I take it that's the intent of 3.5, but punishing a lack of system mastery is not so hot.