I also note you are comparing a desktop OS to a server OS. And 32 bit vs 64 bit. Virtualized too by any chance? Did you update all stats with a full scan after upgrading the database?
As others have said, there are about a bajillion things that could normally cause this type of behavior, and you have compounded that with at least the items above.
Best,
Kevin G. Boles
SQL Server Consultant
SQL MVP 2007-2012
TheSQLGuru on googles mail service