Wanted to point out an issue I ran into at a previous client. I was doing a migration to Exchange and Lync online for the client and the client was primarily running Windows XP as the client OS. I made sure to ask in the sales cycle that they had SP3 on all XP boxes, the client said yes. They based this on reviewing their WSUS reports and noting that none of the XP machines were missing/needing a Service Pack. I also sent the client this site which details the client requirements for Office 365, http://www.microsoft.com/en-us/office365/system-requirements.aspx#fbid=b_ypwK7x5Q2
This is a good site that seems pretty straight forward, showing all the client requirements, both for Windows and Macs.
So fast forward about three weeks, we had the Hybrid solution and SSO with ADFS setup. We had already migrated several of the IT staff and things were going pretty good. The client then went to run the Desktop Setup tool from the Portal on a Windows XP x64 machine and it failed. After looking over the issue and further research I found that Windows XP x64 does not have a SP3 install available, here’s a quick explaination http://social.technet.microsoft.com/forums/en-US/itproxpsp/thread/615782c1-cfdd-44e4-8bd5-f63c1bb98f2a/
Basically XP x64 is based on Server 2003 x64 kernel and no SP3 will be released for XP x64, SP2 is the latest for it.
So please double check your XP versions when planning a migration to Office 365. We ended up having to migrate the workstations running XP x64 to Windows 7 to get them to be supported for Office 365.