I believe running Windows on any hard drive, whether it be in RAID or stand alone will only score a max of 5.9 in WEI. To break that barrier and get an actual rating, Solid State Drives are the way to go. They're pretty expensive, but very worth it!
Also, if you want a higher performing hard drive.... Newegg.com - Seagate Barracuda XT ST32000641AS 2TB 7200 RPM 64MB Cache SATA 6.0Gb/s 3.5" Internal Hard Drive -Bare Drive
This will be your best bet. A rule of thumb for hard drive performance is how dense the platters are for data, meaning the hard drive can pack say 200 gigs in the first three or so centimeters on the outer edge of the hard disk, which is the fastest part, compared to 100.