Don't be fooled by a RAID 0, benchmarks will tell you you're getting about double the transfer rate, but in real world applications, the difference isn't nearly as noticable as benchmarks will lead one to believe.
SATAII seems to be the best of the best right now.
Also, hard drives are not measured in hertz/megahertz/gigahertz as they do not perform instructions.
Intel C2D E6320 / AMD Athlon X2 3800+
Gigabyte 965P DS3 / DFI nF4 Ultra-D
2GB OCZ Gold PC2-6400 / 2GB OCZ Gold PC4000
eVGA 8800GTS 320MB / eVGA 6800GS 256MB
150GB Raptor / 74GB Raptor
2x500GB / 320GB
OCZ GameXStreme 850w / OCZ StealthXStream 600w