Quick Xbox 360 Microsoft Points question

If I use microsoft points to buy DLC for a game (specifically, the Assassins Creed 2 extra missions), and later delete it from my hard drive, can I download it again to the same console & acct for free, or would I have to purchase it again?

All purchases made on Live are tracked and tied to your account. Anything you purchased can be downloaded again free of charge. I have one of the old 20GB hard drives and I have to occasionally clear stuff off to free up space and have done this a couple of times myself.

One caveat is that occasionally things get shuffled off Live and when that happens they can’t be downloaded again. A handful of old Midway games recently got pulled for example, probably due to the ongoing legal matters. This mainly applies to smaller titles though, old arcade games or obscure indie stuff. For something as big as AC2 DLC I don’t think you’d have to worry about that.