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.
Kevin G. Boles
SQL Server Consultant
SQL MVP 2007-2012
TheSQLGuru on googles mail service