Jack - never heard of this - are you sure it for a HDD and not a ReadyBoost device?
SDD is just too expensive at the moment

Confusion still reigns... 7,200 RPM disks with SATA-II connections have a transfer rate of 3Gbps whilst the Raptors are only available as SATA-I so the transfer rate is 1.5Gbps.
I know seek time on Raptors are about half that of the 7,2000 RPM disk, but it looks like the sustained rate would knock the performance of these drives. I suppose it depends how fragmented the drive is, cause it would normally need to do lots of seeks to read back a file.
Maybe SCSI and 15K disk would be an idea

(and a money pit)