@ mdixson, There is no such HDD feature as SATAII so you obv dont know what your talking about.
I think you mean SATA300 and its makes ZERO difference to any single HDD, only the interface at MOBO if you Raid HDD's and get near 300MB/Sec.
SATA300 was new and WD did state they prefered to use a more mature interface at that time.
sorry I forget being on a computing degree means I know nothing about plator density and its effects on performance when coupled with sataII/300 ...