Windows is Dead
The best upgrade on can do is away from Microsoft products entirely and into the open office / Linux environment. For year we have paid a premium for Microsoft products only to require constant retraining, endure their lack of internal quality control and the almost deliberate back doors for virus writers that all Microsoft products seem to embrace. Have you ever noticed how all MS products run slower over time almost forcing the migration to a newer OS/Office... etc? So skip the white papers from some MS certified hack and investigate the stable, refined and mature world of computing that Red Hat and Unbuntu provide. You may also find that simply upgrading to an open source OS actually out performs the latest MS bloatware running on a machine with twice the horsepower - I tried it and it does!