Is this the PC market?
NO
Are those HDD's portable?
NO
Do those HDD's come with a pre-loaded game, trailers, and demos?
NO
The reason why the PS2 HDD wasn't supported was because it
CAME REALLY LATE, was very limited, was never really capitilized upon and (IIRC) required rather extensive support from the developer. The Xbox 360 HDD will be promoted at launch. The two are totally different.