Okay, so last night I purchased MW2 from the marketplace.
As soon as I began the download, the bar went to 1%. About 15 minutes later I checked back and it was still at 1% and then the notification bar popped up saying cannot download Modern Warfare 2. I tried to re-download several times now and the same thing just happens over and over regardless.
The download is a little under 7Gb and I have just under 40Gb free space. I've tried the other suggestions about deleting cache, deleting and re-downloading etc.
Other downloads work, I can still download trials or videos or whatever else as normal.
This is my internet upload/download speed check result: http://www.speedtest.net/result/1325280099.png
Anyone have any idea what is going on? I don't like paying £39.99 for it not to work.