For the person below: £14 is how much 1600 points would cost if you broke the price down into pence per point. I think it's off by about 20p but thats what rounding up does. So yeah, the price is pretty reasonable, and really handy for people who don't want to waste money buying points they're not going to use after buying a game online.
Unfortunately I still have 1000 points to waste, so I'm going to have to fork out for another 1000 seeing as they don't sell 600 points alone, even on the MS marketplace, which is a bit sly. Hence 4 stars
And for the person who asked, these are xbox live points. You can spend them on anything, not just GTA. Works just the same as the 2100 or 4200 cards.