I agree about the diagonal braces; could have sworn that somewhere in the thread you mentioned a plan to wrap the stand in some sort of decorative wood, which would have provided all the bracing necessary.
If that is no longer in the cards, or if I'm mistaken about that, you don't even need to cut any lumber to put in the braces. IKEA, believe it or not, sells pairs of steel rods joined into an X shape with a single screw at the centre, which allows them to be formed to fit almost any piece of furniture to act as braces. They are actually sold for use with one of the generic IKEA neo-Euro-crap modulaar bookcases, but they work for tank stands beautifully. Cost a couple bucks, install in a couple seconds, very low-profile and unobtrusive, add huge stability and three-dimensional support.
Okay, there goes...the first and last time I ever recommend IKEA to anybody.
So...what's the going rate for a smashed kid nowadays?