Just one last question.
The WD Raptor 150GB is significantly faster than the 74GB version.
The difference between them is the 8MB of cache.
So does this mean that 16MB of cache really DO matter for raptors and that would explain why they are starting to make 74GB raptors with 16MB now?
It more or less has to do with the number of platters and the areal density of them. That and it is of the later generation (microcode improvements anyone?) so there are sure to be small tweaks.
If you are deciding between the 74Gb and the 150Gb - if you have the money to spend I'd go with the 150Gb. Alternatively, You could get the 74Gb and use it as your main (OS/Swap/some games) and then with the money saved buy a 320Gb drive and put your office/productivity apps and saved information on them.