From what I understand, it would be best to actually download the game, including patches (wow, lotro, etc.) from a wifi access point. I was told from a friend that playing the game on mobile broadband doesn't actually use up much during gameplay.
Is there any other information about the usage available, even an estimate? I came here for this exact same answer myself, but I can't afford to test it and see, just in case it does use up all my mb for the month.. Im a student, $50 is alot of money. 
Hi guys,
I actually do a lot of xbox live gaming on my MIFI. Here's what I have found out. It uses about 25MB per hour. So you can play a little less than 4 hours and it will use 100 MB. I have been studying this for 3 months. I wrote down when I logged on to xbox live and when I logged off. I used my connection strictly for xbox live only so I could inform other people that it is possible to use the MIFI for online gaming.
Here's my situation:
I did not want to spend the money on a wireless adapter (microsoft money-making scheme). Instead, I tether my MIFI device to my desktop PC and then share my connection to my xbox. At first I had trouble getting the xbox to recognize the IP address but I learned to start the computer, connect device, connect to internet, and then start the xbox which took care of the problem.
I have been playing a lot of Halo:REACH which still only uses 25MB per hour. But I was bored the other day and popped in GTA IV which only used 15MB per hour!! I think this is due to the fact the map was pretty well preloaded.
It is doable as long as you monitor your usage which is sometimes difficult when verizon gets behind on updating their accounts but people need to use common sense. If you watched 25 youtube videos the day before its probably a good idea to stay off xbox live for a day to make sure you don't use up your 5GB limit.
Hope this helps 
