Remember when Xbox LIVE was young, and the only available point values to purchase were 500, 1000 , etc? Those values were strange, because they didn't match the cost of the games and you always had strange leftover amounts. On a $5 (400) game, you had 100 leftover useless MSPoints (which is approximate $1.50). On a $10 (800) game, you had 200 unused MSPoints leftover. Not enough to do anything with, but no refunds on your real-life money.
Well, Microsoft has changed it's available bundle packs on Xbox LIVE when you purchase from your console. Now, if you want that $5 (400) or $10 (800) awesome co-op game, you can get the right amount of MSPoints to spend, without unsightly leftovers. The restructure matches much more closely to what the actual Arcade games/add-on packs cost. We, as gamers, like this. It's less wasted money that just sits lonely, unloved, and completely worthless on our Xbox account.
Now go. Download something.