As far as advanced format, it's a mixed bag that depends on your usage (dealing more with lots of small files or fewer smaller files).
In either case, however, you won't notice significant performance gains; this deals more with allocating physical space on the hdd--not necessarily storage space.
See: http://www.pcguide.com/ref/hdd/perf/perf/spec/otherCach... for more information.
Steaming movies and MS Office are not very demanding applications, so you may not need the ultimate HDD speed. Personally, I'm no big fan of RAID0 because of its increased risk of failure and loss, although you are doing regular backups - good for you! But RAID0's main advantage - speed - may be of no real use to you in those applications. On the other hand, the Green line (5400 rpm) of HDD's is slower than the WD Black line (7200 rpm), and that's why they put the 64 MB of cache on the unit - to compensate for the slightly slower seek times. Theoretically, though, streaming movies is a sequential file access mode, and that's where a large cache does its best work to help out.