Goes beyond putting the files up in the cloud but how would you use said content. So far I haven't found Microsoft to offer much beyond Exchange Server with it's Outlook Web version to let you get access to that PST.
Maybe Office 365 comes close?
It's over at http://www.microsoft.com/en-us/office365/online-software.aspx#fbid=Esn2y48Hvfz
Bob
I have about 60GB+ of data from an old Windows computer that I'd like to have available where ever I go, but I don't want to carry a spare drive or flash drive. I'd like to have it safely stored on the cloud but don't want a mirror of that much data stored locally like Dropbox does.

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