PST Capture 2.0 is a great tool from Microsoft and works really well when migrating PST files into Exchange Online. I recently had a problem when trying to select destination mailboxes , The solution is really simple. You need to get your tenant server name and you can do this by browsing to www.outlook.com/contoso.com and taking note of the server name and then entering it in the Exchange Online settings in PST capture as per the image below.
You can download PST Capture 2.0 HERE
PST capture requires Outlook 2010 x64
You can download Office 2010 x64 Service Pack 2 HERE
October 2013 Cumulative updates for Outlook 2010 can be downloaded HERE
Office365 Single Signin Assistant can be downloaded HERE