You actually can never really tell how much a game will use exactly. Especially with a game such as MW2
where every map is different, uses different amount of gigs for download, especially with different kill streaks being used as well. The best way is to record what gigs you have left, turn off everything that uses net except your ps3, play an hour, then record again and calculate the difference.
my parents are my back about how they much data i use when i play online and im sick of them on my back about it and they think 1GB/hr and i have been trying to tell them its heaps less that but i gave up for 2 months and i started back playing BO when they ask me im over the stage where i just wanna get rid of my ps3 and BO grrr
Suggest to them that for one day - Midnight to midnight nothing connects to the internet except for the PS3 - then play for a set period of time. Next day check the account with you ISP and there is your evidence.
i played my ps3 for 8hrs before i had used 17GB now i have used 30GB whats going on??
The mb/hour is defined by your ISP so speak to them to see what they have alocated for online gaming.
Sometimes you will need to do an update for the game thats on top of your mb/hour.
If you download games and or demos then again thats the same as above.