This question came up during the training class on Tuesday in which I was answering questions behind the scenes.  I did not have the answer then but here is the help file for file sizes for OneNote on Skydrive: http://office.microsoft.com/en-us/onenote-help/resolve-the-0xe0000025-file-too-large-error-in-onenote-HA102938202.aspx

Sorry I did not have it then.

Questions, comments, concerns and criticisms always welcome,
John